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FLYING  MACHINES  TODAY 


"Hitherto  aviation  has  been  almost  monopolized  by  that  much-over- 
praised and  much-overtrusted  person,  'the  practical  man.'  It  is  much  in 
need  of  the  services  of  the  theorist  —  the  engineer  with  his  mathematical 
calculations  of  how  a  flying  machine  ought  to  be  built  and  of  how  the 
material  used  in  its  construction  should  be  distributed  to  give  the  greatest 
possible  amount  of  strength  and  efficiency." 

—  From  the  New  York  Times,  January  16,  1911. 


FLYING    MACH  INES 
TODAY 


BY 
WILLIAM    DUANE    ENNIS 

Professor  of  Mechanical  Engineering  in  the  Polytechnic 
Institute  of  Brooklyn 


123  ILLUSTRATIONS 


NEW  YORK 
D.   VAN    NOSTRAND    COMPANY 

23  MURRAY  AND  1911  27  WARREN  STS. 


5"'/7 


Copyright,  1911,  by 
D.  VAN  NOSTRAND  COMPANY 


THE  •  PLIMPTON  •  PRESS  •  NORWOOD  •  MASS  •  U  •  S  •  A 


€0 
MY    MOTHER 


223083 


PREFACE 

SPEAKING  with  some  experience,  the  writer  has  found 
that  instruction  in  the  principles  underlying  the  science 
and  sport  of  aviation  must  be  vitalized  by  some  contem- 
poraneous study  of  what  is  being  accomplished  in  the  air. 
No  one  of  the  revolutionizing  inventions  of  man  has  pro- 
gressed as  rapidly  as  aerial  navigation.  The  " truths"  of 
today  are  the  absurdities  of  tomorrow. 

The  suggestion  that  some  grasp  of  the  principles  and  a 
very  fair  knowledge  of  the  current  practices  in  aeronautics 
may  be  had  without  special  technical  knowledge  came 
almost  automatically.  If  this  book  is  comprehensible  to 
the  lay  reader,  and  if  it  conveys  to  him  even  a  small  pro- 
portion of  the  writer's  conviction  that  flying  machines  are 
to  profoundly  influence  our  living  in  the  next  generation, 
it  will  have  accomplished  its  author's  purpose. 


POLYTECHNIC  INSTITUTE  OF  BROOKLYN, 
NEW  YORK,  April,  1911. 


CONTENTS 

PAGE 

THE  DELIGHTS  AND   DANGERS  OF  FLYING.  —  DANGERS 

OF  AVIATION.  —  WHAT  IT  is  LIKE  TO  FLY i 

SOARING  FLIGHT  BY  MAN.—  WHAT  HOLDS  IT  UP?  — LIFT- 
ING POWER. — WHY  so  MANY  SAILS?  —  STEERING  ...  17 

TURNING  CORNERS.  —  WHAT  HAPPENS  WHEN  MAKING  A 
TURN.  —  LATERAL  STABILITY.  —  WING  WARPING.  —  AUTO- 
MATIC CONTROL.  —  THE  GYROSCOPE.  —  WIND  GUSTS  ...  33 

AIR    AND    THE     WIND.  —  SAILING   BALLOONS.  —  FIELD    AND 

SPEED 43 

GAS   AND    BALLAST. — BUOYANCY  IN   AIR.  —  ASCENDING  AND 

DESCENDING. — THE   BALLONET.  —  THE   EQUILIBRATOR    .      .       57 

DIRIGIBLE    BALLOONS  AND   OTHER  KINDS.  — SHAPES.— 
DIMENSIONS.  —  FABRICS.  —  FRAMING.  —  KEEPING   THE   KEEL 
HORIZONTAL. — STABILITY. —  RUDDERS  AND  PLANES. — ARRANGE- 
MENT AND  ACCESSORIES.  —  AMATEUR  DIRIGIBLES. — THE  FORT 
OMAHA  PLANT.  —  BALLOON  PROGRESS 71 

THE  QUESTION  OF  POWER.  —  RESISTANCE  OF  AEROPLANES.  - 
RESISTANCE  OF  DIRIGIBLES.  — :  INDEPENDENT  SPEED  AND 
TIME-TABLE.  —  THE  COST  OF  SPEED. — THE  PROPELLER  .  101 

GETTING  UP  AND  DOWN;  MODELS  AND  GLIDERS; 
AEROPLANE  DETAILS. — LAUNCHING.  —  DESCENDING.— 
GLIDERS.  —  MODELS.  —  BALANCING.  —  WEIGHTS.  —  MISCEL- 
LANEOUS.—  THINGS  TO  LOOK  AFTER 121 

SOME   AEROPLANES.  — SOME   ACCOMPLISHMENTS     .      .     143 

THE  POSSIBILITIES  IN  AVIATION.  —  THE  CASE  OF  THE 
DIRIGIBLE.  —  THE  ORTHOPTER.  —  THE  HELICOPTER.  —  COM- 
POSITE TYPES. —  WHAT  is  PROMISED 170 

AERIAL    WARFARE 189 


XI 


LIST   OF   ILLUSTRATIONS 


PAGE 

The  Fall  of  Icarus Frontispiece 

The  Aviator 3 

The  Santos-Dumont  "Demoiselle'1 4 

View  from  a  Balloon 9 

Anatomy  of  a  Bird's  Wing 10 

Flight  of  a  Bird n 

In  a  Meteoric  Shower 13 

How  a  Boat  Tacks 15 

Octave  Chanute 18 

Pressure  of  the  Wind 10 

Forces  Acting  on  a  Kite 20 

Sustaining  Force  in  the  Aeroplane 23 

Direct  Lifting  and  Resisting  Forces 24 

Shapes  of  Planes 26 

Balancing  Sail 28 

Roe's  Triplane  at  Wembley 30 

Action  of  the  Steering  Rudder ^31 

Recent  Type  of  Wright  Biplane 31 

Circular  Flight 33 

The  Aileron 35 

Wing  Tipping 36 

Wing  Warping 37 

The  Gyroscope .  39 

Diurnal  Temperatures  at  Different  Heights 45 

Seasonal  Variation  in  Wind  Velocities 47 

The  Wind  Rose  for  Mt.  Weather,  Va 49 

Diagram  of  Parts  of  a  Drifting  Balloon 51 

Glidden  and  Stevens  Getting  Away  in  the  "Boston"     ....  52 

Relative  and  Absolute  Balloon  Velocities 53 

Field  and  Speed 53 

Influence  of  Wind  on  Possible  Course 54 

Count  Zeppelin  .......      .  ~T"  .      .      .      .      .      .  55 

Buoyant  Power  of  Wood 57 

One  Cubic  Foot  of  Wood  Loaded  in  Water  .      .-    .      .  -  .      .      .  58 

xiii 


xiv  List  of  Illustrations 

PAGE 

Buoyant  Power  of  Hydrogen 59 

Lebaudy's  "Jaune" 60 

Air  Balloon 62 

Screw  Propeller  for  Altitude  Control 66 

Balloon  with  Ballonets 67 

Construction  of  the  Zeppelin  Balloon 68 

The  Equilibrator 69 

Henry  Giffard's  Dirigible 71 

Dirigible  of  Dupuy  de  Lome 72 

Tissandier  Brothers'  Dirigible  Balloon 73 

The  "Baldwin" 74 

The  "Zeppelin"  on  Lake  Constance  . 75 

The"Patrie" 77 

Manufacturing  the  Envelope  of  a  Balloon 79 

Andree's  Balloon,  "L'Oernen" 80 

Wreck  of  the  "Zeppelin" 82 

Car  of  the  "Zeppelin" 84 

Stern  View  of  the  "Zeppelin" 86 

The  " Clement-Bayard"  .      .      .      .    1 87 

The  "  Ville  de  Paris " 88 

Car  of  the  " Liberte"      .^> 89 

The  "Zodiac  No.  2" 92 

United  States  Signal  Corps  Balloon  Plant  at  Fort  Omaha        .      .  93 

The  "Caroline-" 94 

The  Ascent  at  Versailles,  1783 95 

Proposed  Dirigible 96 

The  " Republique " 97 

The  First  Flight  for  the  Gordon-Bennett  Cup    .      .      ..-_..  99 

The  Gnome  Motor 102 

Screw  Propeller  ........  ;.-."••  .     v     .      .    *:      .  103 

One  of  the  Motors  of  the  "Zeppelin"      .    "\      .      .      .      .      .      .  104 

The  Four-Cycle  Engine       .      ....    .      .      .     ".,-    .      .      .     :.      .  105 

Action  of  Two-Cycle  Engine    .      .      .      .  •'. -    '.  ~  .      .     .•      •      •  IQ6 

Motor  and  Propeller      ....      .      .      .      .      .      .     ,.      .      .  108 

Two-Cylinder  Opposed  Engine      .      .      .      ...      :      .      .      .  no' 

Four-Cylinder  Vertical  Engine      ^     .      .      .   \T      .      .      ^     .      •  no 

Head  End  Shapes     .      .     '.      .    ..      .      .      .      .      .      .      .      •      •  JI3 

The  Santos-Dumont  Dirigible  No.  2  .      .      . 115 

In  the  Bay  of  Monaco:  Santos-Dumont        ...      .      .      .      .  117 

Wright  Biplane  on  Starting  Rail   .      .      .J 121 

Launching  System  for  Wright  Aeroplane 122 


List  of  Illustrations  xv 

PAGE 

The  Nieuport  Monoplane  .             124 

A  Biplane 125 

Ely  at  Los  Angeles 126 

Trajectory  During  Descent 127 

Descending 128 

The  Witteman  Glider 130 

French  Monoplane 132 

A  Problem  in  Steering 133 

Lejeune  Biplane 134 

Tellier  Monoplane 135 

A  Monoplane 137 

Cars  and  Framework 139 

Some  Details 139 

Recent  French  Machines 141 

Orville  Wright  at  Fort  Myer 143 

The  First  Flight  Across  the  Channel 144 

Wright  Motor 145 

Voisin-Farman  Biplane 147 

The  Champagne  Grand  Prize  Flight .      .      .  148 

Farman's  First  Biplane 149 

The  "June  Bug" 150 

Curtiss  Biplane 151 

Curtiss' Hydro- Aeroplane  at  San  Diego  Bay 152 

Flying  Over  the  Water 153 

Bleriot-Voisin  Cellular  Biplane  with  Pontoons 154 

Latham's  "Antoinette" 155 

James  J.  Ward  at  Lewiston  Fair 156 

Marcel  Penot  in  the  "Mohawk" 157 

Santos-Dumont's  "Demoiselle" 159 

Bleriot  Monoplane 160 

Latham's  Fall  into  the  Channel 161 

De  Lesseps  Crossing  the  Channel 163 

The  Maxim  Aeroplane 164 

Langley's  Aeroplane 165 

Robart  Monoplane *66 

Vina  Monoplane 167 

Blanc  Monoplane I7° 

Melvin  Vaniman  Triplane i?1 

Jean  de  Crawhez  Triplane        .      .      . i?1 

A  Triplane -."    .      ,     ..    ' .     ,"     ,      ...      ...  172 

Giraudon's  Wheel  Aeroplane    .      *      .      ....      .      .      .      .  *75 


xvi  List  of  Illustrations 

PAGE 

Breguet  Gyroplane  (Helicopter)    ......  I?- 

Wellman's  "America" xgj 

The  German  Emperor  Watching  the  Progress  of  Aviation    .  189 

Automatic  Gun  for  Attacking  Airships IQ3 

Gun  for  Shooting  at  Aeroplanes IQ7 

Santos-Dumont  Circling  the  Eiffel  Tower IQ9 

Latham,  Farman  and  Paulhan      .... 


FLYING  MACHINES  TODAY 


THE  DELIGHTS  AND   DANGERS  OF  FLYING 

FEW  things  have  more  charm  for  man  than  flight.  The 
soaring  of  a  bird  is  beautiful  and  the  gliding  of  a  yacht 
before  the  wind  has  something  of  the  same  beauty.  The 
child's  swing;  the  exercise  of  skating  on  good  ice;  a  sixty- 
mile-an-hour  spurt  on  a  smooth  road  in  a  motor  car;  even 
the  slightly  passe  bicycle:  these  things  have  all  in  their 
time  appealed  to  us  because  they  produce  the  illusion  of 
flight  —  of  progress  through  the  intangible  air  with  all 
but  separation  from  the  prosaic  earth. 

But  these  sensations  have  been  only  illusions.  To  actu- 
ally leave  the  earth  and  wander  at  will  in  aerial  space  — 
this  has  been,  scarcely  a  hope,  perhaps  rarely  even  a  dis- 
tinct dream.  From  the  days  of  Daedalus  and  Icarus,  of 
Oriental  flying  horses  and  magic  carpets,  down  to  "Darius 
Green  and  his  flying  machine,"  free  flight  and  frenzy  were 
not  far  apart.  We  were  learnedly  told,  only  a  few  years 
since,  that  sustention  by  heavier- than-air  machines  was 
impossible  without  the  discovery,  first,  of  some  new 
matter  or  some  new  force.  It  is  now  (1911)  only  eight 
years  since  Wilbur  Weight  at  Kitty  Hawk,  with  the  aid  of 
the  new  (?)  matter  —  aluminum  —  and  the  "new"  force  — 
the  gasoline  engine  —  in  three  successive  flights  proved 
that  a  man  could  travel  through  the  air  and  safely  descend, 


2  Flying  Machines  Today 

in  a  machine  weighing  many  times  as  much  as  the  air  it 
displaced.  It  is  only  five  years  since  two  designers  — 
Surcouf  and  Lebaudy  —  built  dirigible  balloons  approxi- 
mating present  forms,  the  Ville  de  Paris  and  La  Patrie. 
It  is  only  now  that  we  average  people  may  confidently 
contemplate  the  prospect  of  an  aerial  voyage  for  ourselves 
before  we  die.  A  contemplation  not  without  its  shudder, 
perhaps;  but  yet  not  altogether  more  daring  than  that  of 
our  grandsires  who  first  rode  on  steel  rails  behind  a  steam 
locomotive. 

THE  DANGERS  OF  AVIATION 

We  are  very  sure  to  be  informed  of  the  fact  when  an 
aviator  is  killed.  Comparatively  little  stir  is  made  now- 
adays over  an  automobile  fatality,  and  the  ordinary  rail- 
road accident  receives  bare  mention.  For  instruction  and 
warning,  accidents  to  air  craft  cannot  be  given  too  much 
publicity;  but  if  we  wish  any  accurate  conception  of 
the  danger  we  must  pay  regard  to  factors  of  proportion. 
There  are  perhaps  a  thousand  aeroplanes  and  about 
sixty  dirigible  balloons  in  the  world.  About  500  men  - 
amateurs  and  professionals  —  are  continuously  engaged 
in  aviation.  The  Aero  Club  of  France  has  issued  in 
that  country  nearly  300  licenses.  In  the  United  States, 
licenses  are  held  by  about  thirty  individuals.  We  can 
form  no  intelligent  estimate  as  to  the  number  of  un- 
licensed amateurs  of  all  ages  who  are  constantly  experi- 
menting with  gliders  at  more  or  less  peril  to  life  and  limb. 

A   French   authority   has    ascertained    the   death   rate 


The  Delights  and  Dangers  of  Flying  3 

among  air-men  to  have  been  —  to  date  —  about  6%. 
This  is  equivalent  to  about  one  life  for  4000  miles  of  flight: 
but  we  must  remember  that  accidents  will  vary  rather 
with  the  number  of  ascents  and  descents  than  with  the 
mileage.  Four  thousand  miles  in  100  flights  would  be 


much  less  perilous,  under  present  conditions,  than  4000 
miles  in  1000  flights. 

There  were  26  fatal  aeroplane  accidents  between  Sep- 
tember 17,  1908,  and  December  3,  1910.  Yet  in  that 
period  there  were  many  thousands  of  ascents:  1300  were 
made  in  one  week  at  the  Rheims  tournament  alone.  Of 


4  Flying  Machines  Today 

the  26  accidents,  i  was  due  to  a  wind  squall,  3  to  collision, 
6  (apparently)  to  confusion  of  the  aviator,  and  12  to  me- 
chanical breakage.  An  analysis  of  40  British  accidents 
shows  13  to  have  been  due  to  engine  failures,  10  to  alighting 
on  bad  ground,  6  to  wind  gusts,  5  to  breakage  of  the 
propeller,  and  6  to  fire  and  miscellaneous  causes.  These 


THE  SANTOS-DUMONT  "DEMOISELLE" 
(From  The  Aeroplane,  by  Hubbard,  Ledeboer  and  Turner) 

casualties  were  not  all  fatal,  although  the  percentage  of 
fatalities  in  aeronautic  accidents  is  high.  The  most  serious 
results  were  those  due  to  alighting  on  bad  ground;  long 
grass  and  standing  grain  being  very  likely  to  trip  the 
machine  and  throw  the  occupant.  French  aviators  are 
now  strapping  themselves  to  their  seats  in  order  to  avoid 
this  last  danger. 


The  Delights  and  Dangers  of  Flying  5 

Practically  all  of  the  accidents  occur  to  those  who  are 
flying;  but  spectators  may  endanger  themselves.  Dur- 
ing one  of  the  flights  of  Mauvais  at  Madrid,  in  March 
of  the  present  year,  the  bystanders  rushed  through  the 
barriers  and  out  on  the  field  before  the  machine  had  well 
started.  A  woman  was  decapitated  by  the  propeller, 
and  four  other  persons  were  seriously  injured. 

Nearly  all  accidents  result  from  one  of  three  causes:  bad 
design,  inferior  mechanical  construction,  and  the  taking  of 
unnecessary  risks  by  the  operator.  Scientific  design  at 
the  present  writing  is  perhaps  impossible.  Our  knowledge 
of  the  laws  of  air  resistance  and  sustention  is  neither 
accurate  nor  complete.  Much  additional  study  and  experi- 
ment must  be  carried  on;  and  some  better  method  of  experi- 
menting must  be  devised  than  that  which  sends  a  man  up 
in  the  air  and  waits  to  see  what  happens.  A  thorough 
scientific  analysis  will  not  only  make  aviation  safer,  it  will 
aid  toward  making  it  commercially  important.  Further 
data  on  propeller  proportions  and  efficiencies,  and  on 
strains  in  the  material  of  screws  under  aerial  conditions, 
will  do  much  to  standardize  power  plant  equipment.  The 
excessive  number  of  engine  breakdowns  is  obviously  related 
to  the  extremely  light  weight  of  the  engines  employed: 
better  design  may  actually  increase  these  weights  over 
those  customary  at  present.  Great  weight  reduction  is  no 
longer  regarded  as  essential  at  present  speeds  in  aerial 
navigation:  we  have  perhaps  already  gone  too  far  in  this 
respect. 


6  Flying  Machines  Today 

Bad  workmanship  has  been  more  or  less  unavoidable, 
since  no  one  has  yet  had  ten  years'  experience  in  building 
aeroplanes.  The  men  who  have  developed  the  art  have 
usually  been  sportsmen  rather  than  mechanics,  and  only 
time  is  necessary  to  show  the  impropriety  of  using  "safety 
pins"  and  bent  wire  nails  for  connections. 

The  taking  of  risks  has  been  an  essential  feature.  When 
one  man  earns  $100,000  in  a  year  by  dare-devil  flights, 
when  the  public  flocks  in  hordes  —  and  pays  good  prices  - 
to  see  a  man  risk  his  neck,  he  will  usually  aim  to  satisfy 
it.  This  is  not  developing  aerial  navigation:  this  is  cir- 
cus riding  —  looping-the-loop  performances  which  appeal 
to  some  savage  instinct  in  us  but  lead  us  nowhere.  Men 
have  climbed  two  miles  into  the  clouds,  for  no  good  pur- 
pose whatever.  All  that  we  need  to  know  of  high  altitude 
conditions  is  already  known  or  may  be  learned  by  ascents 
in  anchored  balloons.  Records  up  to  heights  of  sixteen 
miles  have  been  obtained  by  sounding  balloons. 

If  these  high  altitudes  may  under  certain  conditions  be 
desirable  for  particular  types  of  balloon,  they  are  essentially 
undesirable  for  the  aeroplane.  The  supporting  power  of  a 
heavier-than-air  machine  decreases  in  precisely  inverse 
ratio  with  the  altitude.  To  fly  high  will  then  involve 
either  more  supporting  surface  and  therefore  a  structurally 
weaker  machine,  or  greater  speed  and  consequently  a  larger 
motor.  It  is  true  that  the  resistance  to  propulsion 
decreases  at  high  altitudes,  just  as  the  supporting  power 
decreases:  and  on  this  account,  given  only  a  sufficient 


The  Delights  and  Dangers  of  Flying  7 

margin  of  supporting  power,  we  might  expect  a  standard 
machine  to  work  about  as  well  at  a  two-mile  elevation  as 
at  a  height  of  200  feet;  but  rarefaction  of  the  air  at  the 
higher  altitudes  decreases  the  weight  of  carbureted  mix- 
ture drawn  into  the  motor,  and  consequently  its  output. 
Any  air-man  who  attempts  to  reach  great  heights  in  a 
machine  not  built  for  such  purpose  is  courting  disaster. 

Flights  over  cities,  spectacular  as  they  are,  and  popular  as 
they  are  likely  to  remain,  are  doubly  dangerous  on  account 
of  the  irregular  air  currents  and  absence  of  safe  landing 
places.  They  have  at  last  been  officially  discountenanced 
as  not  likely  to  advance  the  sport. 

All  flights  are  exhibition  flights.  The  day  of  a  quiet, 
mind-your-own-business  type  of  aerial  journey  has  not 
yet  arrived.  Exhibition  performances  of  any  sort  are 
generally  hazardous.  There  were  nine  men  killed  in  one 
recent  automobile  meet.  If  the  automobile  were  used 
exclusively  for  races  and  contests,  the  percentage  of  fatali- 
ties might  easily  exceed  that  in  aviation.  It  is  claimed  that 
no  inexperienced  aviator  has  ever  been  killed.  This  may 
not  be  true,  but  there  is  no  doubt  that  the  larger  number 
of  accidents  has  occurred  to  the  better-known  men  from 
whom  the  public  expects  something  daring. 

Probably  the  best  summing  up  of  the  danger  of  aviation 
may  be  obtained  from  the  insurance  companies.  The 
courts  have  decided  that  an  individual  does  not  forfeit 
his  life  insurance  by  making  an  occasional  balloon  trip. 
Regular  classified  rates  for  aeroplane  and  balloon  operators 


8  Flying  Machines  Today 

are  in  force  in  France  and  Germany.  It  is  reported  that 
Mr.  Grahame- White  carries  a  life  insurance  policy  at  35% 
premium  —  about  the  same  rate  as  that  paid  by  a  "  crowned 
head."  Another  aviator  of  a  less  professional  type  has 
been  refused  insurance  even  at  40%  premium.  Policies 
of  insurance  may  be  obtained  covering  damage  to  ma- 
chines by  fire  or  during  transportation  and  by  collisions 
with  other  machines;  and  covering  liability  for  injuries  to 
persons  other  than  the  aviator. 

On  the  whole,  flying  is  an  ultra-hazardous  occupation; 
but  an  occasional  flight  by  a  competent  person  or  by  a 
passenger  with  a  careful  pilot  is  simply  a  thrilling  experi- 
ence, practically  no  more  dangerous  than  many  things 
we  do  without  hesitation.  Nearly  all  accidents  have  been 
due  to  preventable  causes;  and  it  is  simply  a  matter  of 
science,  skill,  perseverance,  and  determination  to  make  an 
aerial  excursion  under  proper  conditions  as  safe  as  a  journey 
in  a  motor  car.  Men  who  for  valuable  prizes  undertake 
spectacular  feats  will  be  killed  as  frequently  in  aviation  as 
in  bicycle  or  even  in  automobile  racing;  but  probably  not 
very  much  more  frequently,  after  design  and  workmanship 
in  flying  machines  shall  have  been  perfected.  The  total 
number  of  deaths  in  aviation  up  to  February  9,  1911,  is 
stated  to  have  been  forty- two. 

WHAT  IT  Is  LIKE  TO  FLY 

We  are  fond  of  comparing  flying  machines  with  birds, 
with  fish,  and  with  ships:  and  there  are  useful  analogies 


io  Flying  Machines  Today 

with  all  three.  A  drifting  balloon  is  like  a  becalmed  ship 
or  a  dead  fish.  It  moves  at  the  speed  of  the  aerial  fluid 
about  it  and  the  occupants  perceive  no  movement  what- 
ever. The  earth's  surface  below  appears  to  move  in  the 
opposite  direction  to  that  in  which  the  wind  carries  the 
balloon.  With  a  dirigible  balloon  or  flying  machine,  the 
sensation  is  that  of  being  exposed  to  a  violent  wind,  against 
which  (by  observation  of  landmarks)  we  find  that  we 


ANATOMY  OF  A  BIRD'S  WING 
(From  Walker's  Aerial  Navigation) 

progress.  It  is  the  same  experience  as  that  obtained  when 
standing  in  an  exposed  position  on  a  steamship,  and  we 
wonder  if  a  bird  or  a  fish  gradually  gets  so  accustomed  to 
the  opposing  current  as  to  be  unconscious  of  it.  But  in 
spite  of  jar  of  motors  and  machinery,  there  is  a  freedom  of 
movement,  a  detachment  from  earth-associations,  in  air 
flight,  that  distinguishes  it  absolutely  from  the  churning 
of  a  powerful  vessel  through  the  waves. 

Birds  fly  in  one  of  three  ways.     The  most  familiar  bird 


12  Flying  Machines  Today 

flight  is  by  a  rapid  wing  movement  which  has  been  called 
oar-like,  but  which  is  precisely  equivalent  to  the  usual 
movement  of  the  arms  of  a  man  in  swimming.  The  edge 
of  the  wing  moves  forward,  cutting  the  air;  on  the  return 
stroke  the  leading  edge  is  depressed  so  as  to  present  a 
nearly  flat  surface  to  the  air  and  thus  propel  the  bird  for- 
ward. A  slight  downward  direction  of  this  stroke  serves 
to  impel  the  flight  sufficiently  upward  to  offset  the  effect 
of  gravity.  Any  man  can  learn  to  swim,  but  no  man  can 
fly,  because  neither  in  his  muscular  frame  nor  by  any  device 
which  he  can  attach  thereto  can  he  exert  a  sufficient  pres- 
sure to  overcome  his  own  weight  against  as  imponderable 
a  fluid  as  air.  If  air  were  as  heavy  as  water,  instead  of 
700  times  lighter,  it  would  be  as  easy  to  fly  as  to  swim. 
The  bird  can  fly  because  of  the  great  surface,  powerful 
construction,  and  rapid  movement  of  its  wings,  in  propor- 
tion to  the  weight  of  its  body.  But  compared  with  the 
rest  of  the  animal  kingdom,  flying  birds  are  all  of  small  size. 
Helmholz  considered  that  the  vulture  represented  the 
heaviest  body  that  could  possibly  be  raised  and  kept  aloft 
by  the  exercise  of  muscular  power,  and  it  is  understood 
that  vultures  have  considerable  difficulty  in  ascending; 
so  much  so  that  unless  in  a  position  to  take  a  short  pre- 
liminary run  they  are  easily  captured. 

Every  one  has  noticed  a  second  type  of  bird  flight  — 
soaring.     It  is  this  flight  which  is  exactly  imitated  in  a 
glider.     An  aeroplane  differs  from  a  soaring  bird  only  in 
that  it  carries  with  it  a  producer  of  forward  impetus  —  the 


The  Delights  and  Dangers  of  Flying  13 

propeller  —  so  that  the  soaring  flight  may  last  indefinitely: 
whereas  a  soaring  bird  gradually  loses  speed  and  descends. 


IN  A  METEORIC  SHOWER 


A  third  and  rare  type  of  bird  flight  has  been  called  sailing. 
The  bird  faces  the  wind,  and  with  wings  outspread  and 
their  forward  edge  elevated  rises  while  being  forced  back- 
ward under  the  action  of  the  breeze.  As  soon  as  the  wind 


14  Flying  Machines  Today 

somewhat  subsides,  the  bird  turns  and  soars  in  the  desired 
direction.  Flight  is  thus  accomplished  without  muscular 
effort  other  than  that  necessary  to  properly  incline  the  wings 
and  to  make  the  turns.  It  is  practicable  only  in  squally 
winds,  and  the  birds  which  practice  " sailing"  —  the 
albatross  and  frigate  bird  —  are  those  which  live  in  the 
lower  and  more  disturbed  regions  of  the  atmosphere.  This 
form  of  flight  has  been  approximately  imitated  in  the 
manceuvering  of  aeroplanes. 

Comparison  of  flying  machines  and  ships  suggests  many 
points  of  difference.  Water  is  a  fluid  of  great  density,  with 
a  definite  upper  surface,  on  which  marine  structures " 
naturally  rest.  A  vessel  in  the  air  may  be  at  any  elevation 
in  the  surrounding  rarefied  fluid,  and  great  attention  is 
necessary  to  keep  it  at  the  elevation  desired.  The  air 
has  no  surface.  The  air  ship  is  like  a  submarine  —  the 
dirigible  balloon  of  the  sea  —  and  perhaps  rather  more 
safe.  An  ordinary  ship  is  only  partially  immersed;  the 
resistance  of  the  fluid  medium  is  exerted  over  a  portion 
only  of  its  head  end:  but  the  submarine  or  the  flying 
machine  is  wholly  exposed  to  this  resistance.  The  sub- 
marine is  subjected  to  ocean  currents  of  a  very  few  miles 
per  hour,  at  most;  the  currents  to  which  the  flying  machine 
may  be  exposed  exceed  a  mile  a  minute.  Put  a  submarine 
in  the  Whirlpool  Rapids  at  Niagara  and  you  will  have 
possible  air  ship  conditions. 

A  marine  vessel  may  tack,  i.e.,  may  sail  partially  against 
the  wind  that  propels  it,  by  skilful  utilization  of  the  resist- 


The  Delights  and  Dangers  of  Flying 


Qo  about 
at  this  point 


Go  about 
at  this  point 


How  a  Boat  Tacks 

The  wind  always  exerts  a  pressure,  per- 
pendicular to  the  sail,  which  tends  to 
drift  the  boat  sidewise  (R  )  and  also  to  propel 
it  forward  (  L  )  .     Sidewise  movement 
is  resisted  by  the  hull. 
An  air  ship  cannot  tack 
because  there  is  no  such 
resistance  to  drift. 


Go  about 
at  this  point 


1 6  Flying  Machines  Today 

ance  to  sidewise  movement  of  the  ship  through  the  water: 
but  the  flying  machine  is  wholly  immersed  in  a  single 
fluid,  and  a  head  wind  is  nothing  else  than  a  head  wind, 
producing  an  absolute  subtraction  from  the  proper  speed 
of  the  vessel. 

Aerial  navigation  is  thus  a  new  art,  particularly  when 
heavier- than-air  machines  are  used.  We  have  no  heavier- 
than-water  ships.  The  flying  machine  must  work  out  its 
own  salvation. 


SOARING  FLIGHT  BY  MAN 
FLYING  machines  have  been  classified  as  follows:  — 

LIGHTER  THAN  AIR 
Fixed  balloon, 
Drifting  balloon, 
Sailing  balloon, 
Dirigible  balloon 

rigid  (Zeppelin), 

ballonetted. 

HEAVIER  THAN  AIR 
Orthopter, 
Helicopter, 
Aeroplane 

monoplane, 
multiplane. 

We  will  fall  in  with  the  present  current  of  popular  interest 
and  consider  the  aeroplane  —  that  mechanical  grasshop- 
per —  first. 

WHAT  HOLDS  IT  UP? 

When  a  flat  surface  like  the  side  of  a  house  is  exposed  to 
the  breeze,  the  velocity  of  the  wind  exerts  a  force  or  pres- 
sure directly  against  the  surface.  This  principle  is  taken 
into  account  in  the  design  of  buildings,  bridges,  and  other 

17 


i8 


Flying  Machines  Today 


OCTAVE  CHANUTE  (died  1910) 

To  the  researches  of  Chanute  and  Langley  must  be 
ascribed  much  cf  American  progress  in  aviation. 


Soaring  Flight  by  Man  19 

structures.  The  pressure  exerted  per  square  foot  of  sur- 
face is  equal  (approximately)  to  the  square  of  the  wind 
velocity  in  miles  per  hour,  divided  by  300.  Thus,  if  the 
wind  velocity  is  thirty  miles,  the  pressure  against  a  house 
wall  on  which  it  acts  directly  is  30  X  30  -f-  300  =  3  pounds 
per  square  foot:  if  the  wind  velocity  is  sixty  miles,  the 
pressure  is  60  X  60  -r-  300  =12  pounds:  if  the  velocity  is 
ninety  miles,  the  pressure  is  90  X  90  -f-  300  =  27  pounds, 
and  so  on. 


If  the  wind  blows  obliquely  toward  the  surface,  instead 
of  directly,  the  pressure  at  any  given  velocity  is  reduced, 
but  may  still  be  considerable.  Thus,  in  the  sketch,  let  ab 
represent  a  wall,  toward  which  we  are  looking  downward, 
and  let  the  arrow  V  represent  the  direction  of  the  wind. 
The  air  particles  will  follow  some  such  paths  as  those 
indicated,  being  deflected  so  as  to  finally  escape  around 
the  ends  of  the  wall.  The  result  is  that  a  pressure  is  pro- 
duced which  may  be  considered  to  act  along  the  dotted 


2O  Flying  Machines  Today 

line  P,  perpendicular  to  the  wall.  This  is  the  invariable 
law:  that  no  matter  how  oblique  the  surface  may  be,  with 
reference  to  the  direction  of  the  wind,  there  is  always  a 
pressure  produced  against  the  surface  by  the  wind,  and 
this  pressure  always  acts  in  a  direction  perpendicular  to  the 
surface.  The  amount  of  pressure  will  depend  upon  the 
wind  velocity  and  the  obliquity  or  inclination  of  the  surface 
(ab)  with  the  wind  (F). 

Now  let  us  consider  a  kite  —  the  "immediate  ancestor'7 
of  the  aeroplane.     The  surface  ab  is  that  of  the  kite  itself, 


held  by  its  string  cd.  We  are  standing  at  one  side  and 
looking  at  the  edge  of  the  kite.  The  wind  is  moving 
horizontally  against  the  face  of  the  kite,  and  produces  a 
pressure  P  directly  against  the  latter.  The  pressure  tends 
both  to  move  it  toward  the  left  and  to  lift  it.  If  the  tend- 
ency to  move  toward  the  left  be  overcome  by  the  string, 
then  the  tendency  toward  lifting  may  be  offset  —  and  in 
practice  is  offset  —  by  the  weight  of  the  kite  and  tail. 

We  may  represent  the  two  tendencies  to  movement 
produced  by  the  force  P,  by  drawing  additional  dotted 
lines,  one  horizontally  to  the  left  (R)  and  the  other  verti- 


Soaring  Flight  by  Man  21 

cally  (L) ;  and  it  is  known  that  if  we  let  the  length  of  the 
line  P  represent  to  some  convenient  scale  the  amount  of 
direct  pressure,  then  the  lengths  of  R  and  L  will  also 
represent  to  the  same  scale  the  amounts  of  horizontal  and 
vertical  force  due  to  the  pressure.  If  the  weight  of  kite  and 
tail  exceeds  the  vertical  force  L,  the  kite  will  descend:  if 
these  weights  are  less  than  that  force,  the  kite  will  ascend. 
If  they  are  precisely  equal  to  it,  the  kite  will  neither  ascend 
nor  descend.  The  ratio  of  L  to  R  is  determined  by  the 
slope  of  P;  and  this  is  fixed  by  the  slope  of  ab;  so  that  we 
have  the  most  important  conclusion:  not  only  does  the 
amount  of  direct  pressure  (P)  depend  upon  the  obliquity  of 
the  surface  with  the  breeze  (as  has  already  been  shown),  but 
the  relation  of  vertical  force  (which  sustains  the  kite)  to  hori- 
zontal force  also  depends  on  the  same  obliquity.  For  example, 
if  the  kite  were  flying  almost  directly  above  the  boy  who 
held  the  string,  so  that  ab  became  almost  horizontal,  P 
would  be  nearly  vertical  and  L  would  be  much  greater 
than  R.  On  the  other  hand,  if  ab  were  nearly  vertical,  the 
kite  flying  at  low  elevation,  the  string  and  the  direct  pres- 
sure would  be  nearly  horizontal  and  L  would  be  much  less 
than  R.  The  force  L  which  lifts  the  kite  seems  to  increase 
while  R  decreases,  as  the  kite  ascends:  but  L  may  not 
actually  increase,  because  it  depends  upon  the  amount  of 
direct  pressure,  P,  as  well  as  upon  the  direction  of  this 
pressure;  and  the  amount  of  direct  pressure  steadily 
decreases  during  ascent,  on  account  of  the  increasing 
obliquity  of  ab  with  V.  All  of  this  is  of  course  dependent 


22  Flying  Machines  Today 

on  the  assumption  that  the  kite  always  has  the  same 
inclination  to  the  string,  and  the  described  resolution  of 
the  forces,  although  answering  for  illustrative  purposes, 
is  technically  incorrect. 

It  seems  to  be  the  wind  velocity,  then,  which  holds  up  the 
kite:  but  in  reality  the  string  is  just  as  necessary  as  the 
wind.  If  there  is  no  string,  and  the  wind  blows  the  kite 
with  it,  the  kite  comes  down,  because  the  pressure  is  wholly 
due  to  a  relative  velocity  as  between  kite  and  wind.  The 
wind  exerts  a  pressure  against  the  rear  of  a  railway  train, 
if  it  happens  to  be  blowing  in  that  direction,  and  if  we 
stood  on  the  rear  platform  of  a  stationary  train  we  should 
feel  that  pressure :  but  if  the  train  is  started  up  and  caused 
to  move  at  the  same  speed  as  the  wind  there  would  be  no 
pressure  whatever. 

One  of  the  very  first  heavier-than-air  flights  ever  recorded 
is  said  to  have  been  made  by  a  Japanese  who  dropped 
bombs  from  an  immense  man-carrying  kite  during  the 
Satsuma  rebellion  of  1869.  The  kite  as  a  flying  machine 
has,  however,  two  drawbacks:  it  needs  the  wind  —  it  can- 
not fly  in  a  calm  —  and  it  stands  still.  One  early  effort 
to  improve  on  this  situation  was  made  in  1856,  when  a 
man  was  towed  in  a  sort  of  kite  which  was  hauled  by  a 
vehicle  moving  on  the  ground.  In  February  of  the  present 
year,  Lieut.  John  Rodgers,  U.  S.N.,  was  lifted  400  feet 
from  the  deck  of  the  cruiser  Pennsylvania  by  a  train  of 
eleven  large  kites,  the  vessel  steaming  at  twelve  knots 
against  an  eight-knot  breeze.  The  aviator  made  obser- 


Soaring  Flight  by  Man  23 

vations  and  took  photographs  for  about  fifteen  minutes, 
while  suspended  from  a  tail  cable  about  100  feet  astern. 
In  the  absence  of  a  sufficient  natural  breeze,  an  artificial 
wind  was  thus  produced  by  the  motion  imparted  to  the 
kite;  and  the  device  permitted  of  reaching  some  destina- 
tion. The  next  step  was  obviously  to  get  rid  of  the  tractive 
vehicle  and  tow  rope  by  carrying  propelling  machinery 
on  the  kite.  This  had  been  accomplished  by  Langley  in 
1896,  who  flew  a  thirty-pound  model  nearly  a  mile,  using  a 
steam  engine  for  power.  The  gasoline  engine,  first  em- 
ployed by  Santos-Dumont  (in  a  dirigible  balloon)  in  1901, 
has  made  possible  the  present  day  aeroplane. 


What  " keeps  it  up,"  in  the  case  of  this  device,  is  likewise 
its  velocity.  Looking  from  the  side,  ab  is  the  sail  of  the 
aeroplane,  which  is  moving  toward  the  right  at  such  speed 
as  to  produce  the  equivalent  of  an  air  velocity  V  to  the 
left.  This  velocity  causes  the  direct  pressure  P,  equivalent 
to  a  lifting  force  L  and  a  retarding  force  R.  The  latter  is 
the  force  which  must  be  overcome  by  the  motor:  the 


24  Flying  Machines  Today 

former  must  suffice  to  overcome  the  whole  weight  of  the 
apparatus.  Travel  in  an  aeroplane  is  like  skating  rapidly 
over  very  thin  ice:  the  air  literally  " doesn't  have  time  to 
get  away  from  underneath." 

If  we  designate  the  angle  made  by  the  wings  (ati)  with 

the  horizontal  (F)  as  B,  then  P  increases  as  B  increases, 

10 


7 


7 


y 


\ 


\ 


3          3 

Angles  in  Degrees 


§  g 


DIRECT,  LIFTING,  AND  RESISTING  FORCES 

If  the  pressure  is  10  Ibs.  when  the  wind  blows  directly  toward  the 
surface  (at  an  angle  of  90  degrees),  then  the  forces  for  other  angles  of 
direction  are  as  shown  on  the  diagram.  The  amounts  of  all  forces  de- 
pend upon  the  wind  velocity:  that  assumed  in  drawing  the  diagram 
was  about  55  miles  per  hour.  But  the  relations  of  the  forces  are  the 
same  for  the  various  angles,  no  matter  what  the  velocity. 

while  (as  has  been  stated)  the  ratio  of  L  to  R  decreases. 
When  the  angle  B  is  a  right  angle,  the  wings  being  in  the 
position  a'b' ',  P  has  its  maximum  value  for  direct  wind  - 
•%%-$  of  the  square  of  the  velocity,  in  pounds  per  square  foot; 
but  L  is  zero  and  R  is  equal  to  P.     The  plane  would  have  no 


Soaring  Flight  by  Man  25 

lifting  power.  When  the  angle  B  becomes  zero,  position 
a"b",  wings  being  horizontal,  P  becomes  zero  and  (so  far 
as  we  can  now  judge)  the  plane  has  neither  lifting  power 
nor  retarding  force.  At  some  intermediate  position,  like 
ab,  there  will  be  appreciable  lifting  and  retarding  forces. 
The  chart  shows  the  approximate  lifting  force,  in  pounds 
per  square  foot,  for  various  angles.  This  force  becomes  a 
maximum  at  an  angle  of  45°  (half  a  right  angle).  We  are 
not  yet  prepared  to  consider  why  in  all  actual  aeroplanes 
the  angle  of  inclination  is  much  less  than  this.  The  reason 
will  be  shown  presently.  At  this  stage  of  the  discussion 
we  may  note  that  the  lifting  power  per  square  foot  of  sail 
area  varies  with 

the  square  of  the  velocity,  and 

the  angle  of  inclination. 

The  total  lifting  power  of  the  whole  plane  will  also  vary 
with  its  area.  As  we  do  not  wish  this  whole  lifting  power 
to  be  consumed  in  overcoming  the  dead  weight  of  the  ma- 
chine itself,  we  must  keep  the  parts  light,  and  in  particular 
must  use  for  the  wings  a  fabric  of  light  weight  per  unit  of 
surface.  These  fabrics  are  frequently  the  same  as  those 
used  for  the  envelopes  of  balloons. 

Since  the  total  supporting  power  varies  both  with  the 
sail  area  and  with  the  -velocity,  we  may  attain  a  given 
capacity  either  by  employing  large  sails  or  by  using  high 
speed.  The  size  of  sails  for  a  given  machine  varies  in- 
versely as  the  square  of  the  speed.  The  original  Wright 
machine  had  500  square  feet  of  wings  and  a  speed  of  forty 


26 


Flying  Machines  Today 


miles  per  hour.  At  eighty  miles  per  hour  the  necessary  sail 
area  for  this  machine  would  be  only  125  square  feet;  and 
at  1 60  miles  per  hour  it  would  be  only  31  \  square  feet: 
while  if  we  attempted  to  run  the  machine  at  ten  miles  per 
hour  we  should  need  a  sail  area  of  8000  square  feet.  This 
explains  why  the  aeroplane  cannot  go  slowly. 

It  would  seem  as  if  when  two  or  more  superposed  sails 
were  used,  as  in  biplanes,  the  full  effect  of  the  air  would 
not  be  realized,  one  sail  becalming  the  other.  Experiments 
have  shown  this  to  be  the  case;  but  there  is  no  great  reduc- 
tion in  lifting  power  unless  the  distance  apart  is  consider- 
ably less  than  the  width  of  the  planes. 

In  all  present  aeroplanes  the  sails  are  concaved  on  the 
under  side.  This  serves  to  keep  the  air  from  escaping 
from  underneath  as  rapidly  as  it  otherwise  would,  and 
increases  the  lifting  power  from  one-fourth  to  one-half  over 
that  given  by  our  3^  rule:  the  divisor  becoming  roughly 
about  230  instead  of  300. 


X  ^ 


Why  are  the  wings  placed  crosswise  of  the  machine, 
when  the  other  arrangement  —  the  greatest  dimension 
in  the  line  of  flight  —  would  seem  to  be  stronger?  This 


Soaring  Flight  by  Man  27 

is  also  done  in  order  to  "keep  the  air  from  escaping  from 
underneath."  The  sketch  shows  how  much  less  easily 
the  air  will  get  away  from  below  a  wing  of  the  bird-like 
spread-out  form  than  from  one  relatively  long  and  narrow 
but  of  the  same  area. 

A  sustaining  force  of  two  pounds  per  square  foot  of  area 
has  been  common  in  ordinary  aeroplanes  and  is  perhaps 
comparable  with  the  results  of  bird  studies:  but  this  figure 
is  steadily  increasing  as  velocities  increase. 

WHY  so  MANY  SAILS? 

Thus  far  a  single  wing  or  pair  of  wings  would  seem  to 
fully  answer  for  practicable  flight:  yet  every  actual  aero- 
plane has  several  small  wings  at  various  points.  The 
necessity  for  one  of  these  had  already  been  discovered  in  the 
kite,  which  is  built  with  a  balancing  tail.  In  the  sketch 
on  page  18  it  appears  that  the  particles  of  air  which  are 
near  the  upper  edge  of  the  surface  are  more  obstructed 
in  their  effort  to  get  around  and  past  than  those  near  the 
lower  edge.  They  have  to  turn  almost  completely  about, 
wThile  the  others  are  merely  deflected.  This  means  that  on 
the  whole  the  upper  air  particles  will  exert  more  pressure 
than  the  lower  particles  and  that  the  " center  of  pressure" 
(the  point  where  the  entire  force  of  the  wind  may  be 
assumed  to  act)  will  be,  not  at  the  center  of  the  surface,  but 
at  a  point  some  distance  above  this  center.  This  action  is 
described  as  the  " displacement  of  the  center  of  pressure." 
It  is  known  that  the  displacement  is  greatest  for  least 


28  Flying  Machines  Today 

inclinations  of  surface  (as  might  be  surmised  from  the 
sketch  already  referred  to),  and  that  it  is  always  propor- 
tional to  the  dimension  of  the  surface  in  the  direction  of 
movement;  i.e.,  to  the  length  of  the  line  ab. 

If  the  weight  W  of  the  aeroplane  acts  downward  at  the 
center  of  the  wing  (at  o  in  the  accompanying  sketch), 
while  the  direct  pressure  P  acts  at  some  point  c  farther 
along  toward  the  upper  edge  of  the  wing,  the  two  forces  W 
and  P  tend  to  revolve  the  whole  wing  in  the  direction 
indicated  by  the  curved  arrow.  This  rotation,  in  an  aero- 


plane, is  resisted  by  the  use  of  a  tail  plane  or  planes,  such 
as  mn.  The  velocity  produces  a  direct  pressure  P'  on  the 
tail  plane,  which  opposes,  like  a  lever,  any  rotation  due  to 
the  action  of  P.  It  may  be  considered  a  matter  of  rather 
nice  calculation  to  get  the  area  and  location  of  the  tail 
plane  just  right:  but  we  must  remember  that  the  amount 
of  pressure  P'  can  be  greatly  varied  by  changing  the  incli- 
nation of  the  surface  mn.  This  change  of  inclination  is 
effected  by  the  operator,  who  has  access  to  wires  which  are 
attached  to  the  pivoted  tail  plane.  It  is  of  course  permis- 
sible to  place  the  tail  plane  in  front  of  the  main  planes  — 


Soaring  Flight  by  Man  29 

as  in  the  original  Wright  machine  illustrated:  but  in  this 
case,  with  the  relative  positions  of  W  and  P  already  shown, 
the  forward  edge  of  the  tail  plane  would  have  to  be  de- 
pressed instead  of  elevated.  The  illustration  shows  the 
tail  built  as  a  biplane,  just  as  are  the  principal  wings 
(page  141). 

Suppose  the  machine  to  be  started  with  the  tail  plane  in  a 
horizontal  position.  As  its  speed  increases,  it  rises  and  at 
the  same  time  (if  the  weight  is  suspended  from  the  center 
of  the  main  planes)  tilts  backward.  The  tilting  can  be 
stopped  by  swinging  the  tail  plane  on  its  pivot  so  as  to 
oppose  the  rotative  tendency.  If  this  control  is  not  carried 
too  far,  the  main  planes  will  be  allowed  to  maintain  some 
of  their  excessive  inclination  and  ascent  will  continue. 
When  the  desired  altitude  has  been  attained,  the  inclina- 
tion of  the  main  planes  will,  by  further  swinging  of  the  tail 
plane,  be  reduced  to  the  normal  amount,  at  which  the 
supporting  power  is  precisely  equal  to  the  load;  and  the 
machine  will  be  in  vertical  equilibrium:  an  equilibrium 
which  demands  at  every  moment,  however,  the  attention 
of  the  operator. 

In  many  machines,  ascent  and  tilting  are  separately 
controlled  by  using  two  sets  of  transverse  planes,  one  set 
placed  forward,  and  the  other  set  aft,  of  the  main  planes. 
In  any  case,  quick  ascent  can  be  produced  only  by  an 
increase  in  the  lifting  force  L  (see  sketch,  page  24)  of  the 
main  planes:  and  this  force  is  increased  by  enlarging  the 
angle  of  inclination  of  the  main  planes,  that  is,  by  a  con- 


30  Flying  Machines  Today 

trolled  and  partial  tilting.  The  forward  transverse  wing 
which  produces  this  tilting  is  therefore  called  the  elevating 
rudder  or  elevating  plane.  The  rear  transverse  plane 
which  checks  the  tilting  and  steadies  the  machine  is  often 


ROE'S  TRIPLANE  AT  WEMBLEY 
(From  Brewer's  Art  of  Aviation) 

described  as  the  stabilizing  plane.  Descent  is  of  course 
produced  by  decreasing  the  angle  of  inclination  of  the  main 
planes. 

STEERING 

If  we  need  extra  sails  for  stability  and  ascent  or  descent, 
we  need  them  also  for  changes  of  horizontal  direction. 
Let  ab  be  the  top  view  of  the  main  plane  of  a  machine, 
following  the  course  xy.  At  rs  is  a  vertical  plane  called  the 
steering  rudder.  This  is  pivoted,  and  controlled  by  the 


Soaring  Flight  by  Man 


31 


operator  by  means  of  the  wires  /,  u.     Let  the  rudder  be 
suddenly  shifted  to  the  position  r's1 '.     It  will  then  be  sub- 


\ 
I 

x'    _-- 


jected  to  a  pressure  P'  which  will  swing  the  whole  machine 
into  the  new  position  shown  by  the  dotted  lines,  its  course 
becoming  x'y' .  The  steering  rudder  may  of  course  be 
double,  forming  a  vertical  biplane,  as  in  the  Wright  ma- 
chine shown  below. 

Successful    steering    necessitates    lateral    resistance    to 
drift,  i.e.,  a  fulcrum.     This  is  provided,  to  some  extent,  by 


Staaring  Rudder  (double) 


Two  Vertical 
Fulcrum  Planes 


RECENT  TYPE  OF  WRIGHT  BIPLANE 


the  stays  and  frame  of  the  machine;  and  in  a  much  more 
ample  way  by  the  vertical  planes  of  the  original  Voisin 
cellular  biplane.  A  recent  Wright  machine  had  vertical 
planes  forward  probably  intended  for  this  purpose. 


32  Flying  Machines  Today 

It  now  begins  to  appear  that  the  aviator  has  a  great 
many  things  to  look  after.  There  are  many  more  things 
requiring  his  attention  than  have  yet  been  suggested.  No 
one  has  any  business  to  attempt  flying  unless  he  is  super- 
latively cool-headed  and  has  the  happy  faculty  of  instinc- 
tively doing  the  right  thing  in  an  emergency.  Give  a 
chauffeur  a  high  power  automobile  running  at  maximum 
speed  on  a  rough  and  unfamiliar  road,  and  you  have  some 
conception  of  the  position  of  the  operator  of  an  aeroplane. 
It  is  perhaps  not  too  much  to  say  that  to  make  the  two 
positions  fairly  comparable  we  should  blindfold  the  chauf- 
feur. 

Broadly  speaking,  designers  may  be  classed  in  one  of 
two  groups  —  those  who,  like  the  Wrights,  believe  in 
training  the  aviator  so  as  to  qualify  him  to  properly  handle 
his  complicated  machine;  and  those  who  aim  to  simplify 
the  whole  question  of  control  so  that  to  acquire  the  neces- 
sary ability  will  not  be  impossible  for  the  average  man. 
If  aviation  is  to  become  a  popular  sport,  the  latter  ideal 
must  prevail.  The  machines  must  be  more  automatic 
and  the  aviator  must  have  time  to  enjoy  the  scenery.  In 
France,  where  amateur  aviation  is  of  some  importance, 
progress  has  already  been  made  in  this  direction.  The  uni- 
versal steering  head,  for  example,  which  not  only  revolves 
like  that  of  an  automobile,  but  is  hinged  to  permit  of 
additional  movements,  provides  for  simultaneous  control 
.  of  the  steering  rudder  and  the  main  plane  warping,  while 
scarcely  demanding  the  conscious  thought  of  the  operator. 


TURNING  CORNERS 

A  YEAR  elapsed  after  the  first  successful  flight  at  Kitty 
Hawk  before  the  aviator  became  able  to  describe  a  circle 
in  the  air.  A  later  date,  1907,  is  recorded  for  the  first 
European  half-circular  flight:  and  the  first  complete 
circuit,  on  the  other  side  of  the  water,  was  made  a  year 
after  that;  by  both  biplane  and  monoplane.  It  was  in 
the  same  year  that  Louis  Bleriot  made  the  pioneer  cross- 
country trip  of  twenty-one  miles,  stopping  at  will  en  route 
and  returning  to  his  starting  point. 

WHAT  HAPPENS  WHEN  MAKING  A  TURN 

We  are  looking  downward  on  an  aeroplane  ab  which 
has  been  moving  along  the  straight  path  cd.  At  d  it  begins 


to  describe  the  circle  de,  the  radius  of  which  is  od,  around 

33 


34  Flying  Machines  Today 

the  center  o.  The  outer  portion  of  the  plane,  at  the  edge 
6,  must  then  move  faster  than  the  inner  edge  a.  We  have 
seen  that  the  direct  air  pressure  on  the  plane  is  propor- 
tional to  the  square  of  the  velocity.  The  direct  pressure 
P  (see  sketch  on  page  22)  will  then  be  greater  at  the  outer 
than  at  the  inner  limb;  the  lifting  force  L  will  also  be  greater 
and  the  outer  limb  will  tend  to  rise,  so  that  the  plane 
(viewed  from  the  rear)  will  take  the  inclined  position  shown 
in  the  lower  view :  and  this  inclination  will  increase  as  long 
as  the  outer  limb  travels  faster  than  the  inner  limb;  that 
is,  as  long  as  the  orbit  continues  to  be  curved.  Very  soon, 
then,  the  plane  will  be  completely  tipped  over. 

Necessarily,  the  two  velocities  have  the  ratio  om:omf\ 
the  respective  lifting  forces  must  then  be  proportional  to 
the  squares  of  these  distances.  The  difference  of  lifting 
forces,  and  the  tendency  to  overturn,  will  be  more  im- 
portant as  the  distances  most  greatly  differ:  which  is  the 
case  when  the  distance  om  is  small  as  compared  with  mm'. 
The  shorter  the  radius  of  curvature,  the  more  dangerous, 
for  a  given  machine,  is  a  circling  flight:  and  in  rounding  a 
curve  of  given  radius  the  most  danger  is  attached  to  the 
machine  of  greatest  spread  of  wing. 

LATERAL  STABILITY 

This  particular  difficulty  has  considerably  delayed  the 
development  of  the  aeroplane.  It  may,  however,  be  over- 
come by  very  simple  methods  —  simple,  at  least  as  far  as 
their  mechanical  features  are  concerned.  If  the  outer 


Turning  Corners  35 

limb  of  the  plane  is  tilted  upward,  it  is  because  the  wind 
pressure  is  greater  there.  The  wind  pressure  is  greater 
because  the  velocity  is  greater.  We  have  only  to  increase 
the  wind  pressure  at  the  inner  limb,  in  order  to  restore 
equilibrium.  This  cannot  be  done  by  adjusting  the  velocity, 
because  the  velocity  is  fixed  by  the  curvature  of  path  re- 
quired: but  the  total  wind  pressure  depends  upon  the  sail 
area  as  well  as  the  velocity;  so  that  by  increasing  the  sur- 
face at  the  inner  limb  we  may  equalize  the  value  of  L,  the 
lifting  force,  at  the  two  ends  of  the  plane.  This  increase 
of  surface  must  be  a  temporary  affair,  to  be  discontinued 
when  moving  along  a  straight  course. 


rc 


0  Side  View 

Bear  View 


s 

THE  AILERON 

Let  us  stand  in  the  rear  of  an  aeroplane,  the  main  wing 
of  which  is  represented  by  ab.  Let  the  small  fan-shaped 
wings  c  and  d  be  attached  near  the  ends,  and  let  the  control 
wires,  e,  f,  passing  to  the  operator  at  g,  be  employed  to  close 
and  unclasp  the  fans.  If  these  fans  are  given  a  forward 
inclination  at  the  top,  as  indicated  in  the  end  view,  they 
will  when  spread  out  exert  an  extra  lifting  force.  A  fan 


36  Flying  Machines  Today 

will  be  placed  at  each  end.  They  will  be  ordinarily  folded 
up:  but  when  rounding  a  curve  the  aviator  will  open  the 
fan  on  the  inner  or  more  slowly  moving  limb  of  the  main 
plane.  This  represents  one  of  the  first  forms  of  the  aileron 
or  wing- tip  for  lateral  control. 

The  more  common  present  form  of  aileron  is  that  shown 
in  the  lower  sketch,  at  s  and  /.  The  method  of  control  is 
the  same. 

The  cellular  Voisin  biplanes  illustrate  an  attempt  at 
self-sufficing  control,  without  the  interposition  of  the  avia- 
tor. Between  the  upper  and  lower  sails  of  the  machine 
there  were  fore  and  aft  vertical  partitions.  The  idea  was 
that  when  the  machine  started  to  revolve,  the  velocity  of 
rotation  would  produce  a  pressure  against  these  partitions 

^^%K, 

Front  View  *V  x  ^Ty' 

WING  TIPPING 

which  would  obstruct  the  tipping.  But  rotation  may  take 
place  slowly,  so  as  to  produce  an  insufficient  pressure  for 
control,  and  yet  be  amply  sufficient  to  wreck  the  apparatus. 
The  use  of  extra  vertical  rudder  planes,  hinged  on  a  hori- 
zontal longitudinal  axis,  is  open  to  the  same  objection. 

WING  WARPING 

In  some  monoplanes  with  the  inverted  V  wing  arrange- 
ment, a  dipping  of  one  wing  answers,  so  to  speak,  to  increase 


Turning  Corners  37 

its  concavity  and  thus  to  augment  the  lifting  force  on  that 
side.  The  sketch  shows  the  normal  and  distorted  arrange- 
ment of  wings:  the  inner  limb  being  the  one  bent  down  in 
rounding  a  curve.  An  equivalent  plan  was  to  change  the 
angle  of  inclination  of  one-half  the  sail  by  swinging  it 
about  a  horizontal  pivot  at  the  center  or  at  the  rear 
edge:  some  machines  have  been  built  with  sails  divided 
in  the  center.  The  obvious  objection  to  both  of  these 
plans  is  that  too  much  mechanism  is  necessary  in  order 
to  distort  what  amounts  to  nearly  half  the  whole  ma- 
chine. They  remind  one  of  Charles  Lamb's  story  of  the 
discovery  of  roast  pig. 
The  distinctive  feature  of  the  Wright  machines  lies  in 


WING  WARPING 

the  warping  or  distorting  of  the  ends  only  of  the  main 
planes.  This  is  made  possible,  not  by  hinging  the  wings  in 
halves,  but  by  the  flexibility  of  the  framework,  which  is 
sufficiently  pliable  to  permit  of  a  considerable  bending 
without  danger.  The  operator,  by  pulling  on  a  stout  wire 
linkage,  may  tip  up  (or  down)  the  corners  ccf  of  the  sails 
at  one  limb,  thus  decreasing  or  increasing  the  effective 
surface  acted  on  by  the  wind,  as  the  case  may  require. 


38  Flying  Machines  Today 

The  only  objection  is  that  the  scheme  provides  one  more 
thing  for  the  aviator  to  think  about  and  manipulate. 

AUTOMATIC  CONTROL 

Let  us  consider  again  the  condition  of  things  when 
rounding  a  curve,  as  in  the  sketch  on  page  32.  As  long 
as  the  machine  is  moving  forward  in  a  straight  line,  the 
operator  sits  upright.  When  it  begins  to  tip,  he  will  un- 
consciously tip  himself  the  other  way,  as  represented  by 
the  line  xy  in  the  rear  view.  Any  bicyclist  will  recognize 
this  as  plausible.  Why  not  take  advantage  of  this  involun- 
tary movement  to  provide  a  stabilizing  force?  If  operat- 
ing wires  are  attached  to  the  aviator's  belt  and  from  thence 
connected  with  ailerons  or  wing-warping  devices,  then  by 
a  proper  proportioning  of  levers  and  surfaces  to  the  prob- 
able swaying  of  the  man,  the  control  may  become  automatic. 
The  idea  is  not  new;  it  has  even  been  made  the  subject  of 
a  patent. 

THE  GYROSCOPE 

This  device  for  automatic  control  is  being  steadily 
developed  and  may  ultimately  supersede  all  others.  It 
uses  the  inertia  of  a  fast-moving  fly  wheel  for  control,  in  a 
manner  not  unlike  that  contemplated  in  proposed  methods 
of  automatic  balancing  by  the  action  of  a  suspended  pendu- 
lum. Every  one  has  seen  the  toy  gyroscope  and  perhaps 
has  wondered  at  its  mysterious  ways.  The  mathematical 
analysis  of  its  action  fills  volumes :  but  some  idea  of  what 
it  does,  and  why,  may  perhaps  be  gathered  at  the  expense 


Turning  Corners  39 

of  a  very  small  amount  of  careful  attention.  The  wheel 
acbd,  a  thin  disc,  is  spinning  rapidly  about  the  axle  o.  In 
the  side  view,  ab  shows  the  edge  of  the  wheel,  and  oo'  the 


End 


THE  GYROSCOPE 


axle.  This  axle  is  not  fixed,  but  may  be  conceived  as  held 
in  some  one's  fingers.  Now  suppose  the  right-hand  end 
of  the  axle  (0')  to  be  suddenly  moved  toward  us  (away 
from  the  paper)  and  the  left-hand  (o)  to  be  moved  away. 


4o  Flying  Machines  Today 

The  wheel  will  now  appear  in  both  views  as  an  ellipse,  and 
it  has  been  so  represented,  as  a/be.  Now,  any  particle,  like 
x,  on  the  rim  of  the  wheel,  will  have  been  regularly  moving 
in  the  circular  orbit  cb.  The  tendency  of  any  body  in 
motion  is  to  move  indefinitely  in  a  straight  line.  The 
cohesion  of  the  metal  of  the  disc  prevents  the  particle  x 
from  flying  off  at  a  straight  line  tangent,  xy,  and  it  is  con- 
strained, therefore,  to  move  in  a  circular  orbit.  Unless 
some  additional  constraint  is  imposed,  it  will  at  least 
remain  in  this  orbit  and  will  try  to  remain  in  its  plane  of 
rotation.  When  the  disc  is  tipped,  the  plane  of  rotation 
is  changed,  and  the  particle  is  required,  instead  of  (so  to 
speak)  remaining  in  the  plane  of  the  paper  —  in  the  side 
view  —  to  approach  and  pass  through  that  plane  at  b  and 
afterward  to  continue  receding  from  us.  Under  ordinary 
circumstances,  this  is  just  what  it  would  do:  but  if,  as  in 
the  gyroscope,  the  axle  oo'  is  perfectly  free  to  move  in  any 
direction,  the  particles  will  refuse  to  change  its  direction 
of  rotation.  Its  position  has  been  shifted:  it  no  longer 
lies  in  the  plane  of  the  paper:  but  it  will  at  least  persist 
in  rotating  in  a  parallel  plane:  and  this  persistence  forces 
the  revolving  disc  to  swing  into  the  new  position  indi- 
cated by  the  curve  kg,  the  axis  being  tipped  into  the 
position  pq.  The  whole  effect  of  all  particles  like  x 
in  the  entire  wheel  will  be  found  to  produce  precisely 
this  condition  of  things:  if  we  undertake  to  change  the 
plane  of  rotation  by  shifting  the  axle  in  a  horizontal 
plane,  the  device  itself  will  (if  not  prevented)  make  a 


Turning  Corners  41 

further  change  in  the  plane  of  rotation  by  shifting  the 
axle  in  a  vertical  plane. 

A  revolving  disc  mounted  on  the  gyroscopic  framework 
therefore  resists  influences  tending  to  change  its  plane  of 
rotation.  If  the  device  is  placed  on  a  steamship,  so  that 
when  the  vessel  rolls  a  change  of  rotative  plane  is  produced, 
the  action  of  the  gyroscope  will  resist  the  rolling  tendency 
of  the  vessel.  All  that  is  necessary  is  to  have  the  wheel 
revolving  in  a  fore  and  aft  plane  on  the  center  line  of  the 
vessel,  the  axle  being  transverse  and  firmly  attached  to 
the  vessel  itself.  A  small  amount  of  power  (consumed  in 
revolving  the  wheel)  gives  a  marked  steadying  effect.  The 
same  location  and  arrangement  on  an  aeroplane  will  suffice 
to  overcome  tendencies  to  transverse  rotation  when  round- 
ing curves.  The  device  itself  is  automatic,  and  requires 
no  attention,  but  it  does  unfortunately  require  power  to 
drive  it  and  it  adds  some  weight. 

The  gyroscope  is  being  tested  at  the  present  time  on 
some  of  the  aeroplanes  at  the  temporary  army  camps 
near  San  Antonio,  Texas. 

WIND  GUSTS 

This  feature  of  aeronautics  is  particularly  important, 
because  any  device  which  will  give  automatic  stability 
when  turning  corners  will  go  far  toward  making  aviation 
a  safe  amusement.  Inequalities  of  velocity  exist  not  only 
on  curves,  but  also  when  the  wind  is  blowing  at  anything 
but  uniform  velocity  across  the  whole  front  of  the  machine. 


42  Flying  Machines  Today 

The  slightest  "flaw"  in  the  wind  means  an  at  least  tempo- 
rary variation  in  lifting  force  of  the  two  arms.  Here  is  a 
pregnant  source  of  danger,  and  one  which  cannot  be  left 
for  the  aviator  to  meet  by  conscious  thought  and  action. 
It  is  this,  then,  that  blindfolds  him:  he  cannot  see  the 
wind  conditions  in  advance.  The  conditions  are  upon 
him,  and  may  have  done  their  destructive  work,  before 
he  can  prepare  to  control  them.  We  must  now  study 
what  these  conditions  are  and  what  their  influence  may 
be  on  various  forms  of  aerial  navigation:  after  which, 
a  return  to  our  present  subject  will  be  possible. 


AIR  AND   THE  WIND 

THE  air  that  surrounds  us  weighs  about  one-thirteenth 
of  a  pound  per  cubic  foot  and  exerts  a  pressure,  at  sea 
level,  of  nearly  fifteen  pounds  per  square  inch.  Its  tem- 
perature varies  from  30°  below  to  100°  above  the  Fahren- 
heit zero.  The  pressure  of  the  air  decreases  about  one- 
half  pound  for  each  thousand  feet  of  altitude;  at  the  top 
of  Mt.  Blanc  it  would  be,  therefore,  only  about  six  pounds 
per  square  inch.  The  temperature  also  decreases  with  the 
altitude.  The  weight  of  a  cubic  foot,  or  density,  which, 
as  has  been  stated,  is  one-thirteenth  of  a  pound  ordinarily ; 
varies  with  the  pressure  and  with  the  temperature.  The 
variation  with  pressure  may  be  described  by  saying  that 
the  quotient  of  the  pressure  by  the  density  is  constant: 
one  varies  in  the  same  ratio  as  the  other.  Thus,  at  the 
top  of  Mt.  Blanc  (if  the  temperature  were  the  same  as  at 
sea  level),  the  density  of  air  would  be  about  •£%  X  iV  =  e2^: 
less  than  half  what  it  is  at  sea  level.  As  to  temperature, 
if  we  call  our  Fahrenheit  zero  460°,  and  correspondingly 
describe  other  temperatures  —  for  instance,  say  that  water 
boils  at  672°  -  -  then  (pressure  being  unchanged)  the  prod- 
uct of  the  density  and  the  temperature  is  constant.  If  the 
density  at  sea  level  and  zero  temperature  is  one-thirteenth 
pound,  then  that  at  sea  level  and  460°  Fahrenheit  would  be 

43 


44  Flying  Machines  Today 

o  +  46o  x    i          i 
460  +  460  > 

These  relations  are  particularly  important  in  the  design 
of  all  balloons,  and  in  computations  relating  to  aeroplane 
flight  at  high  altitudes.  We  shall  be  prepared  to  appreciate 
some  of  their  applications  presently. 

Generally  speaking,  the  atmosphere  is  always  in  motion, 
and  moving  air  is  called  wind.  Our  meteorologists  first 
studied  winds  near  the  surface  of  the  ground:  it  is  only 
of  late  years  that  high  altitude  measurements  have  been 
considered  practically  desirable.  Now,  records  are  ob- 
tained by  the  aid  of  kites  up  to  a  height  of  nearly  four 
miles:  estimates  of  cloud  movements  have  given  data 
on  wind  velocities  at  heights  above  six  miles:  and  much 
greater  heights  have  been  obtained  by  free  balloons  equipped 
with  instruments  for  recording  temperatures,  pressures, 
altitude,  time,  and  other  data. 

When  the  Eiffel  Tower  was  completed,  it  was  found  that 
the  average  wind  velocity  at  its  summit  was  about  four 
times  that  at  the  base.  Since  that  time,  much  attention 
has  been  given  to  the  contrasting  conditions  of  surface  and 
upper  breezes  as  to  direction  and  velocity. 

Air  is  easily  impeded  in  its  movement,  and  the  well- 
known  uncertainties  of  the  weather  are  closely  related  to 
local  variations  in  atmospheric  pressure  and  temperature. 
When  near  the  surface  of  the  ground,  impingement  against 
irregularities  therein  —  hills,  cliffs,  and  buildings  —  makes 
the  atmospheric  currents  turbulent  and  irregular.  Where 


Air  and  the  Wind 


45 


there  are  no  surface  irregularities,  as  on  a  smooth  plain 
or  over  water,  the  friction  of  the  air  particles  passing  over 
the  surface  still  results  in  a  stratification  of  velocities. 
Even  on  a  mountain  top,  the  direction  and  speed  of  the 
wind  are  less  steady  than  in  the  open  where  measured  by 
a  captive  balloon.  The  stronger  the  wind,  the  greater, 
relatively,  is  the  irregularity  produced  by  surface  condi- 
tions. Further,  the  earth's  surface  and  its  features  form  a 


IBM. 


(1) 


15  MITRES 


1500 


\ 


DIURNAL  TEMPERATURES  AT  DIFFERENT  HEIGHTS 
(From  Rotch's  The  Conquest  of  the  Air) 

vast  sponge  for  sun  heat,  which  they  transfer  in  turn  to  the 
air  in  an  irregular  way,  producing  those  convectional  cur- 
rents peculiar  to  low  altitudes,  the  upper  limit  of  which  is 
marked  by  the  elevation  of  the  cumulus  clouds.  Near  the 
surface,  therefore,  wind  velocities  are  lowest  in  the  early 
morning,  rising  to  a  maximum  in  the  afternoon. 

Every   locality   has   its    so-called    " prevailing   winds." 
Considering  the  compass  as  having  eight  points,  one  of 


46  Flying  Machines  Today 

those  points  may  describe  as  many  as  40%  of  all  the  winds 
at  a  given  place.  The  direction  of  prevalence  varies  with 
the  season.  The  range  of  wind  velocities  is  also  a  matter  of 
local  peculiarity.  In  Paris,  the  wind  speed  exceeds  thirty- 
four  miles  per  hour  on  only  sixty-eight  days  in  the  average 
year,  and  exceeds  fifty-four  miles  on  only  fifteen  days. 
Observations  at  Boston  show  that  the  velocity  of  the  wind 
exceeds  twenty  miles  per  hour  on  half  the  days  in  winter 
and  on  only  one-sixth  the  days  in  summer.  Our  largest 
present  dirigible  balloons  have  independent  speeds  of 
about  thirty-four  miles  per  hour  and  are  therefore  available 
(at  some  degree  of  effectiveness)  for  nearly  ten  months  of 
the  year,  in  the  vicinity  of  Paris.  In  a  region  of  low  wind 
velocities  —  like  western  Washington,  in  this  country  — 
they  would  be  available  a  much  greater  proportion  of  the 
time.  To  make  the  dirigible  able  to  at  least  move  nearly 
every  day  in  the  average  year  — in  Paris  —  it  must  be 
given  a  speed  of  about  fifty-five  miles  per  hour. 

Figures  as  to  wind  velocity  mean  little  to  one  unaccus- 
tomed to  using  them.  A  five-mile  breeze  is  just  "  pleas- 
ant." Twelve  miles  means  a  brisk  gale.  Thirty  miles 
is  a  high  wind:  fifty  miles  a  serious  storm  (these  are  the 
winds  the  aviator  constantly  meets):  one  hundred  miles 
is  perhaps  about  the  maximum  hurricane  velocity. 

As  we  ascend  from  the  surface  of  the  earth,  the  wind 
velocity  steadily  increases;  and  the  excess  velocity  of 
winter  winds  over  summer  winds  is  as  steadily  augmented. 
Thus,  Professor  Rotch  found  the  following  variations: 


Air  and  the  Wind 


47 


ALTITUDE  IN  FEET 

656 

1, 800 

3,280 

8,190 
11,440 
17,680 
20,970 
31,100 

ALTITUDE  IN  FEET 

656  to    3,280 

3,280  to    9,810 

9,810  to  16,400 

16,400  to  22,950 

22,950  to  29,500 


ANNUAL  AVERAGE 
WIND  VELOCITY,  FEET  PER  SECOND 

23-I5 
32.10 

35- 
41. 

50.8 

81.7 

89. 

II7-5 

AVERAGE  WIND  VELOCITIES,  FEET  PER  SECOND 
Summer  Winter 


24-55 
26.85 

34.65 
62.60 
77.00 


28.80 
48.17 
71.00 
161.5 
177.0 


These  results  are  shown  in  a  more  striking  way  by  the 


leu 

170 
160 
150 
140 

§130 
Il20 
1.110 

.2    90 

|so 

•3    70 
•§'    60 
£    50 
40 
30 
20 
10 

/ 

7 

/ 

^ 

t 

/ 

X 

^ 

^x 

X 

•  •o^/ 

™ 

^x 

^eP' 

<^ 

^ 

>1 

^X|X 

^ 

^^ 

** 

X 

xk^0 

x 

^^ 

Jj'^1 

Xx 

X 

^ 

^ 

^ 

^ 

^ 

it** 

x 

•^ 

x^* 

V 

^x 

^ 

x 

5000       10000       15000       20000        25000      30000 
Altitude  in  Feet 

chart.     At  a  five  or  six  mile  height,  double-barreled  hur- 
ricanes at  speeds  exceeding  200  miles  per  hour  are  not 


48  Flying  Machines  Today 

merely  possible;   they  are  part  of  the  regular  order  of 
things,  during  the  winter  months. 

The  winds  of  the  upper  air,  though  vastly  more  power- 
ful, are  far  less  irregular  than  those  near  the  surface:  and 
the  directions  of  prevailing  winds  are  changed.  If  50% 
of  the  winds,  at  a  given  location  on  the  surface,  are  from 
the  southwest,  then  at  as  moderate  an  elevation  as  even 
1000  feet,  the  prevailing  direction  will  cease  to  be  from 
southwest;  it  may  become  from  west-southwest;  and  the 
proportion  of  total  winds  coming  from  this  direction  will 
not  be  50%.  These  factors  are  represented  in  meteorologi- 
cal papers  by  what  is  known  as  the  wind  rose.  From  the 
samples  shown,  we  may  note  that  40%  of  the  surface 
winds  at  Mount  Weather  are  from  the  northwest;  while 
at  some  elevation  not  stated  the  most  prevalent  of  the 
winds  (22%  of  the  total)  are  westerly.  The  direction  of 
prevalence  has  changed  through  one-eighth  of  the  possible 
circle,  and  in  a  counter-clockwise  direction.  This  is  con- 
trary to  the  usual  variation  described  by  the  so-called 
Broun's  Law,  which  asserts  that  as  we  ascend  the  direc- 
tion of  prevalence  rotates  around  the  circle  like  the  hands 
of  a  watch;  being,  say,  from  northwest  at  the  surface, 
from  north  at  some  elevation,  from  northeast  at  a  still 
higher  elevation,  and  so  on.  At  a  great  height,  the  change 
in  direction  may  become  total:  that  is,  the  high  altitude 
winds  blow  in  the  exactly  opposite  direction  to  that  of  the 
surface  winds.  In  the  temperate  regions,  most  of  the 
high  altitude  winds  are  from  the  west:  in  the  tropics, 


5o  Flying  Machines  Today 

the  surface  winds  blow  toward  the  west  and  toward  the 
equator;  being  northeasterly  in  the  northern  hemisphere 
and  southeasterly  in  the  southern:  and  there  are  un- 
doubtedly equally  prevalent  high- altitude  counter- trades. 
The  best  flying  height  for  an  aeroplane  over  a  flat  field 
out  in  the  country  is  perhaps  quite  low  —  200  or  300  feet: 
but  for  cross-country  trips,  where  hills,  rivers,  and  buildings 
disturb  the  air  currents,  a  much  higher  elevation  is  neces- 
sary; perhaps  2000  or  3000  feet,  but  in  no  case  more  than 
a  mile.  The  same  altitude  is  suitable  for  dirigible  balloons. 
At  these  elevations  we  have  the  conditions  of  reasonable 
warmth,  dryness,  and  moderate  wind  velocities. 

SAILING  BALLOONS 

In  classifying  air  craft,  the  sailing  balloon  was  mentioned 
as  a  type  intermediate  between  the  drifting  balloon  and 
the  dirigible.  No  such  type  has  before  been  recognized: 
but  it  may  prove  to  have  its  field,  just  as  the  sailing  vessel 
on  the  sea  has  bridged  the  gap  between  the  raft  and  the 
steamship.  It  is  true  that  tacking  is  impossible,  so  that 
our  sailing  balloons  must  always  run  before  the  wind:  but 
they  possess  this  great  advantage  over  marine  sailing  craft, 
that  by  varying  their  altitude  they  may  always  be  able  to 
find  a  favorable  wind.  This  implies  adequate  altitude 
control,  which  is  one  of  the  problems  not  yet  solved  for 
lighter- than-air  flying  machines:  but  when  it  has  been 
solved  we  shall  go  far  toward  attaining  a  dirigible  balloon 
without  motor  or  propeller;  a  true  sailing  craft. 


Air  and  the  Wind 


This  means  more  study  and  careful  utilization  of  strati- 
fied atmospheric  currents.  Professor  Rotch  suggests  the 
utilization  of  the  upper  westerly  wind  drift  across  the 
American  continent  and  the  Atlantic  Ocean,  which  would 
carry  a  balloon  from  San  Francisco  to  southern  Europe  at 


STIFFENER 

SAFETY  VALVE 


SAFETY  VALVE  CORD 


RIPPING  STRIP 


RIP  STRIP  CORD 


FINAL  STITCHES 


FIRST  KNOTS 
SECOND  KNOTS 
THIRD  KNOTS 


OPENING  FOR  CORD 


COLLAR 
SUSPENDING  CORDS 


-ANCHOR 

DIAGRAM  or  PARTS  OF  A  DRIFTING  BALLOON 

a  speed  of  about  fifty  feet  per  second — thirty-four  miles 
per  hour.  Then  by  transporting  the  balloon  to  northern 
Africa,  the  northeast  surface  trade  wind  would  drive  it 
back  to  the  West  Indies  at  twenty-five  miles  per  hour. 
This  without  any  motive  power:  and  since  present  day 
dirigibles  are  all  short  of  motive  power  for  complete 


Flying  Machines  Today 


dirigibility,  we  must  either  make  them  much  more  power- 
ful or  else  adopt  the  sailing  principle,  which  will  permit  of 


GLDDDEN  AND  STEVENS  GETTING  AWAY  IN  THE  "  BOSTON  " 
(Leo  Stevens,  N.Y.) 

actually  decreasing  present  sizes  of  motors,  or  even  possibly 
of  omitting  them  altogether.  Our  next  study  is,  then, 
logically,  one  of  altitude  control  in  balloons. 


Air  and  the  Wind  53 

FIELD  AND  SPEED 

An  aerostat  (non-dirigible  balloon),  unless  anchored, 
drifts  at  the  speed  of  the  wind.  To  the  occupants,  it  seems 
to  stand  still,  while  the  surface  of  the  earth  below  appears 
to  move  in  a  direction  opposite  to  that  of  the  wind.  In 
the  sketch,  if  the  independent  velocity  of  a  dirigible  balloon 


be  PB,  the  wind  velocity  PV,  then  the  actual  course  pur- 
sued is  PR,  although  the  balloon  always  points  in  the 
direction  PB,  as  shown  at  i  and  2.  If  the  speed  of  the  wind 
exceed  that  of  the  balloon,  there  will  be  some  directions 
in  which  the  latter  cannot  progress.  Thus,  let  PV  be  the 


wind  velocity  and  TV  the  independent  speed  of  the  balloon. 
The  tangents  PX,  PX',  include  the  whole  " field  of  action" 
possible.  The  wind  direction  may  change  during  flight, 


54 


Flying  Machines  Today 


so  that  the  initial  objective  point  may  become  unattain- 
able, or  an  initially  unattainable  point  may  be  brought 
within  the  field.  The  present  need  is  to  increase  inde- 
pendent speeds  from  thirty  or  forty  to  fifty  or  sixty  miles 
per  hour,  so  that  the  balloon  will  be  truly  dirigible  (even  if 
at  low  effectiveness)  during  practically  the  whole  year. 


Albany 


"T 


s.s.w. 


Suppose  a  dirigible  to  start  on  a  trip  from  New  York 
to  Albany,  150  miles  away.  Let  the  wind  be  a  twenty-five 
mile  breeze  from  the  southwest.  The  wind  alone  tends  to 
carry  the  balloon  from  New  York  to  the  point  d  in  four 
hours.  If  the  balloon  meanwhile  be  headed  due  west,  it 
would  need  an  independent  velocity  of  its  own  having  the 
same  ratio  to  that  of  the  wind  as  that  of  de  tofd,  or  about 
seventeen  and  one-half  miles  per  hour.  Suppose  its  inde- 


Air  and  the  Wind  55 

pendent  speed  to  be  only  twelve  and  one-half  miles;  then 
after  four  hours  it  will  be  at  the  position  &,  assuming 
it  to  have  been  continually  headed  due  west,  as  indicated 


COUNT  ZEPPELIN 


at  a.    It  will  have  traveled  northward  the  distance  fe, 
apparently  about  sixty-nine  miles. 

After  this  four  hours  of  flight,  the  wind  suddenly  changes 
to  south-southwest.     It  now  tends  to  carry  the  balloon  to 


56  Flying  Machines  Today 

g  in  the  next  four  hours.  Meanwhile  the  balloon,  heading 
west,  overcomes  the  easterly  drift,  and  the  balloon  actually 
lands  at  c.  Unless  there  is  some  further  favorable  shift 
of  the  wind  it  cannot  reach  Albany.  If,  during  the  second 
four  hours,  its  independent  speed  could  have  been  increased 
to  about  fifteen  and  a  half  miles  it  would  have  just  made  it. 
The  actual  course  has  been  fbc :  a  drifting  balloon  would 
have  followed  the  course  fdh,  dh  being  a  course  parallel 
to  bg. 


GAS  AND   BALLAST 


A  CUBICAL  block  of  wood  measuring  twelve  inches  on  a 
side  floats  on  water  because  it  is  lighter  than  water;  it 
weighs,  if  yellow  pine,  thirty-eight  pounds,  whereas  the 
same  volume  of  water  weighs  about  sixty-two  pounds. 
Any  substance  weighing  more  than  sixty-two  pounds  to 
the  cubic  foot  would  sink  in  water. 


Drilled  Hole, 
Plugged  with  Lead 


BUOYANT  POWER  OF  WOOD 

If  our  block  of  wood  be  drilled,  and  lead  poured  in  the 
hole,  the  total  size  of  wood-and-lead  block  being  kept  con- 
stantly at  one  cubic  foot,  the  block  will  sink  as  soon  as  its 
whole  weight  exceeds  sixty- two  pounds.  Ignoring  the 
wood  removed  by  boring  (as,  compared  with  the  lead 
which  replaces  it,  an  insignificant  amount),  the  weight  of 
lead  plugged  in  may  reach  twenty-four  pounds  before  the 
block  will  sink. 

This  figure,  twenty-four  pounds,  the  difference  between 

57 


Flying  Machines  Today 


sixty-two  and  thirty-eight  pounds,  then  represents  the 
maximum  buoyant  power  of  a  cubic  foot  of  wood  in  water. 
It  is  the  difference  between  the  weight  of  the  wood  block 
and  the  weight  of  the  water  it  displaces.  If  any  weight 


3.6  Inches  out 
of  Water 


Just  immersed 


ONE  CUBIC  FOOT  OF  WOOD  LOADED  IN  WATER 

less  than  this  is  added  to  that  of  the  wood,  the  block  will 
float,  projecting  above  the  water's  surface  more  or  less, 
according  to  the  amount  of  weight  buoyed  up.  It  will  not 
rise  entirely  from  the  water,  because  to  do  this  it  would 
need  to  be  lighter,  not  only  than  water,  but  than  air. 

BUOYANCY  IN  AIR 

There  are  gases,  if  not  woods,  lighter  than  air:  among 
them,  coal  gas  and  hydrogen.  A  "bubble"  of  any  of  these 
gases,  if  isolated  from  the  surrounding  atmosphere,  cannot 
sink  but  must  rise.  At  the  same  pressure  and  tempera- 
ture, hydrogen  weighs  about  one-fifteenth  as  much  as  air; 
coal  gas,  about  one-third  as  much.  If  a  bubble  of  either 
of  these  gases  be  isolated  in  the  atmosphere,  it  must  con- 
tinually rise,  just  as  wood  immersed  in  water  will  rise  when 


Gas  and  Ballast 


59 


liberated.  But  the  wood  will  stop  when  it  reaches  the  sur- 
face of  the  water,  while  there  is  no  reason  to  suppose  that 
the  hydrogen  or  coal  gas  bubbles  will  ever  stop.  The  hydro- 
gen bubble  can  be  made  to  remain  stationary  if  it  is  weighted 
down  with  something  of  about  fourteen  times  its  own 
weight  (thirteen  and  one-half  times,  accurately).  Perhaps 
it  would  be  better  to  say  that  it  would  still  continue  to  rise 


- 


of  Lead 


BUOYANT  POWER  OF  HYDROGEN 

slowly  because  that  additional  something  would  itself  dis- 
place some  additional  air;  but  if  the  added  weight  is  a 
solid  body,  its  own  buoyancy  in  air  is  negligible. 

Our  first  principle  is,  then,  that  at  the  same  pressure 
and  temperature,  any  gas  lighter  than  air,  if  properly 
confined,  will  exert  a  net  lifting  power  of  (n — i)  times 
its  own  weight,  where  n  is  the  ratio  of  weights  of  air  and 
gas  per  cubic  foot. 

If  the  pressures  and  temperatures  are  different,  this 
principle  is  modified.  In  a  balloon,  the  gas  is  under  a 


Gas  and  Ballast  61 

pressure  slightly  in  excess  of  that  of  the  external  atmos- 
phere: this  decreases  its  lifting  power,  because  the  weight 
of  a  given  volume  of  gas  is  greater  as  the  pressure  to  which 
it  is  subjected  is  increased.  The  weight  of  a  given  volume 
we  have  called  the  density:  and,  as  has  been  stated,  if  the 
temperature  be  unchanged,  the  density  varies  directly  as 
the  pressure. 

The  pressure  in  a  balloon  is  only  about  i%  greater  than 
that  of  the  atmosphere  at  sea  level,  so  that  this  factor  has 
only  a  slight  influence  on  the  lifting  power.  That  it  leads 
to  certain  difficulties  in  economy  of  gas  will,  however,  soon 
be  seen. 

The  temperature  of  the  gas  in  a  balloon,  one  might 
think,  would  naturally  be  the  same  as  that  of  the  air  out- 
side: but  the  surface  of  the  balloon  envelope  has  an  absorb- 
ing capacity  for  heat,  and  on  a  bright  sunny  day  the  gas 
may  be  considerably  warmed  thereby.  This  action  in- 
creases the  lifting  power,  since  increase  of  temperature 
(the  pressure  remaining  fixed)  decreases  the  density  of  a 
gas.  To  avoid  this  possibly  objectionable  increase  in 
lifting  power,  balloons  are  sometimes  painted  with  a  non- 
absorbent  color.  One  of  the  first  Lebaudy  balloons  re- 
ceived a  popular  nickname  in  Paris  on  account  of  the  yellow 
hue  of  its  envelope. 

Suppose  we  wish  a  balloon  to  carry  a  total  weight, 
including  that  of  the  envelope  itself,  of  a  ton.  If  of  hydro- 
gen, it  will  have  to  contain  one  fifteenth  of  this  weight  or 
about  133  pounds  of  that  gas,  occupying  a  space  of  about 


62  Flying  Machines  Today 

23,000  cubic  feet.  If  coal  gas  is  used,  the  size  of  the 
balloon  would  have  to  be  much  greater.  If  hot  air  is  used 
-as  has  sometimes  been  the  case  —  let  us  assume  the 
temperature  of  the  air  inside  the  envelope  such  that  the 
density  is  just  half  that  of  the  outside  air.  This  would 
require  a  temperature  probably  about  500°.  The  air 


(Photo  by  Paul  Thompson,  N.Y.) 

AIR  BALLOON 
Built  by  some  Germans  in  the  backwoods  of  South  Africa 

needed  would  be  just  a  ton,  and  the  balloon  would  be 
of  about  52,000  cubic  feet.  It  would  soon  lose  its  lifting 
power  as  the  air  cooled;  and  such  a  balloon  would  be 
useful  only  for  short  flights. 

The   23,000  cubic  foot  hydrogen  balloon,   designed  to 
carry  a  ton,  would  just  answer  to  sustain  the  weight.     If 


Gas  and  Ballast  63 

anchored  at  sea  level,  it  would  neither  fall  to  the  ground 
nor  tug  upward  on  its  holding-down  ropes.  In  order  to 
ascend,  something  more  is  necessary.  This  "something 
more"  might  be  some  addition  to  the  size  and  to  the 
amount  of  hydrogen.  Let  us  assume  that  we,  instead,  drop 
one  hundred  pounds  of  our  load.  Thus  relieved  of  so  much 
ballast,  the  balloon  starts  upward,  under  the  net  lifting 
force  of  one  hundred  pounds.  It  is  easy  to  calculate  how 
far  it  will  go.  It  will  not  ascend  indefinitely,  because,  as 
the  altitude  increases,  the  pressure  (and  consequently  the 
density)  of  the  external  atmosphere  decreases.  At  about 
a  2ooo-foot  elevation,  this  decrease  in  density  will  have 
been  sufficient  to  decrease  the  buoyant  power  of  the  hydro- 
gen to  about  1900  pounds,  and  the  balloon  will  cease  to 
rise,  remaining  at  this  level  while  it  moves  before  the 
wind. 

There  are  several  factors  to  complicate  any  calculations. 
Any  expansion  of  the  gas  bag  —  stretching  due  to  an  in- 
crease in  internal  pressure — would  be  one;  but  the  envelope 
fabrics  do  not  stretch  much;  there  is  indeed  a  very  good 
reason  why  they  must  not  be  allowed  to  stretch.  The 
pressure  in  the  gas  bag  is  a  factor.  If  there  is  no  stretching 
of  the  bag,  this  pressure  will  vary  directly  with  the  tem- 
perature of  the  gas,  and  might  easily  become  excessive 
when  the  sun  shines  on  the  envelope. 

A  more  serious  matter  is  the  increased  difference  between 
the  internal  pressure  of  the  gas  and  the  external  pressure 
of  the  atmosphere  at  high  altitudes.  Atmospheric  pres- 


64  Flying  Machines  Today 

sure  decreases  as  we  ascend.  The  difference  between  gas 
pressure  and  air  pressure  thus  increases,  and  it  is  this 
difference  of  pressure  which  tends  to  burst  the  envelope. 
Suppose  the  difference  of  pressure  at  sea  level  to  have 
been  two- tenths  of  a  pound.  For  a  balloon  of  twenty  feet 
diameter,  this  would  give  a  stress  on  the  fabric,  per  lineal 
inch,  of  twenty-four  pounds.  At  an  altitude  of  2000  feet, 
the  atmospheric  pressure  would  decrease  by  one  pound, 
the  difference  of  pressures  would  become  one  and  two-tenths 
pounds,  and  the  stress  on  the  fabric  would  be  144  pounds 
per  lineal  inch  —  an  absolutely  unpermissible  strain. 
There  is  only  one  remedy:  to  allow  some  of  the  gas  to 
escape  through  the  safety  valve;  and  this  will  decrease  our 
altitude. 

ASCENDING  AND  DESCENDING 

To  ascend,  then,  we  must  discard  ballast:  and  we  can- 
not ascend  beyond  a  certain  limit  on  account  of  the  limit 
of  allowable  pressure  on  the  envelope  fabric.  To  again 
descend,  we  must  discharge  some  of  the  gas  which  gives 
us  lifting  power.  Every  change  of  altitude  thus  involves 
a  loss  either  of  gas  or  of  ballast.  Our  vertical  field  of 
control  may  then  be  represented  by  a  series  of  oscillations 
of  gradually  decreasing  magnitude  until  finally  all  power 
to  ascend  is  gone.  And  even  this  situation,  serious  as  it 
is,  is  made  worse  by  the  gradual  but  steady  leakage  of 
gas  through  the  envelope  fabric.  Here,  in  a  word,  is  the 
whole  problem  of  altitude  regulation.  Air  has  no  surface 


Gas  and  Ballast  65 

of  equilibrium  like  water.  Some  device  supplementary  to 
ballast  and  the  safety  valve  is  absolutely  necessary  for 
practicable  flight  in  any  balloon  not  staked  to  the  ground. 

A  writer  of  romance  has  equipped  his  aeronautic  heroes 
with  a  complete  gas-generating  plant  so  that  all  losses 
might  be  made  up;  and  in  addition,  heating  arrangements 
were  provided  so  that  when  the  gas  supply  had  been  par- 
tially expended  its  lifting  power  could  be  augmented  by 
warming  it  so  as  to  decrease  its  density  below  even  the 
normal.  There  might  be  something  to  say  in  favor  of 
this  latter  device,  if  used  in  connection  with  a  collapsible 
gas  envelope. 

Methods  of  mechanically  varying  the  size  of  the  balloon, 
so  as  by  compressing  the  gas  to  cause  descent  and  by  giving 
it  more  room  to  increase  its  lifting  power  and  produce 
ascent,  have  been  at  least  suggested.  The  idea  of  a  vacuum 
balloon,  in  which  a  rigid  hollow  shell  would  be  exhausted 
of  its  contents  by  a  continually  working  pump,  may  appear 
commendable.  Such  a  balloon  would  have  maximum 
lifting  power  for  its  size;  but  the  weight  of  any  rigid  shell 
would  be  considerable,  and  the  pressure  tending  to  rupture 
it  would  be  about  100  times  that  in  ordinary  gas  balloons. 

It  has  been  proposed  to  carry  stored  gas  at  high  pressure 
(perhaps  in  the  liquefied  condition)  as  a  supplementary 
method  of  prolonging  the  voyage  while  facilitating  vertical 
movements :  but  hydrogen  gas  at  a  pressure  of  a  ton  to  the 
square  inch  in  steel  cylinders  would  give  an  ultimate  lift- 
ing power  of  only  about  one-tenth  the  weight  of  the  cylin- 


66  Flying  Machines  Today 

ders  which  contain  it.  These  cylinders  might  be  regarded 
as  somewhat  better  than  ordinary  ballast:  but  to  throw 
them  away,  with  their  gas  charge,  as  ballast,  would  seem 
too  tragic.  Liquefied  gas  might  possibly  appear  rather 
more  desirable,  but  would  be  altogether  too  expensive. 

If  a  screw  propeller  can  be  used  on  a  steamship,  a  dirigible 
balloon,  or  an  aeroplane  to  produce  forward  motion,  there 
is  no  reason  why  it  could  not  also  be  used  to  produce  up- 
ward motion  in  any  balloon;  and  the  propeller  with  its 


.^Equilibrating  Propeller 

T 

<^ 

I  > 

A            <ff 

(Engine 

UF^-  ^ 

1          Gears 

^-Equilibrating  Propeller 

SCREW  PROPELLER  FOR  ALTITUDE  CONTROL 

operating  machinery  would  be  a  substitute  for  twice  its 
equivalent  in  ballast,  since  it  could  produce  motion  either 
upward  or  downward.  Weight  for  weight,  however,  the 
propeller  and  engine  give  only  (in  one  computed  case) 
about  half  the  lifting  power  of  hydrogen.  If  we  are  to  use 
the  screw  for  ascent,  we  might  well  use  a  helicopter,  heavier 
than  air,  rather  than  a  balloon. 

THE  BALLONET 

The   present   standard   method   of   improving   altitude 
regulation  involves  the  use  of  the  ballonet,  or  compartment 


Gas  and  Ballast  67 

air  bag,  inside  the  main  envelope.  For  stability  and 
effective  propulsion,  it  is  important  that  the  balloon  pre- 
serve its  shape,  no  matter  how  much  gas  be  allowed  to 
escape.  Dirigible  balloons  are  divided  into  two  types, 
according  to  the  method  employed  for  maintaining  the 
shape.  In  the  Zeppelin  type,  a  rigid  internal  metal  frame- 
work supports  the  gas  envelope.  This  forms  a  series  of 
seventeen  compartments,  each  isolated  from  the  others. 
No  matter  what  the  pressure  of  gas,  the  shape  of  the 
balloon  is  unchanged. 

In  the  more  common  form  of  balloon,  the  internal 
air  ballonet  is  empty,  or  nearly  so,  when  the  main 
envelope  is  full.  As  gas  is  vented  from  the  latter, 
air  is  pumped  into  the  former.  This  compresses  the 
remaining  gas  and  thus  preserves  the  normal  form  of  the 
balloon  outline. 

But  the  air  ballonet  does  more  than  this.     It  provides 

Gas  Valve 


Valves  ^ 
BALLOON  WITH  BALLONETS 


an  opportunity  for  keeping  the  balloon  on  a  level  keel, 
for  by  using  a  number  of  compartments  the  air  can  be 
circulated  from  one  to  another  as  the  case  may  require, 
thus  altering  the  distribution  of  weights.  Besides  this,  if 


68 


Flying  Machines  Today 


Gas  and  Ballast 


69 


the  pressure  in  the  air  ballonet  be  initially  somewhat 
greater  than  that  of  the  external  atmosphere,  a  consider- 
able ascent  may  be  produced  by  merely  venting  this  air 
ballonet.  This  involves  no  loss  of  gas;  and  when  it  is 
again  desired  to  descend,  air  may  be  pumped  into  the  bal- 
lonet. If  any  considerable  amount  of  gas  should  be 
vented,  to  produce  quick  and  rapid  descent,  the  pumping 
of  air  into  the  ballonet  maintains  the  shape  of  the  balloon 
and  also  facilitates  the  descent. 

THE  EQUILIBRATOR 

Suppose  a  timber  block  of  one  square  foot  area,  ten  feet 
long,  weighing  380  pounds,   to  be  suspended  from  the 


6.09  ft-Immersed 
gives  Equilibrium 


THE  EQUILIBRATOR  IN  NEUTRAL  POSITION 

balloon  in  the  ocean,  and  let  mechanism  be  provided  by 
which  this  block  may  be  raised  or  lowered  at  pleasure. 
When  completely  immersed  in  water  it  exerts  an  upward 


yo  Flying  Machines  Today 

pressure  (lifting  force)  of  240  pounds,  which  may  be  used 
to  supplement  the  lifting  power  of  the  balloon.  If  wholly 
withdrawn  from  the  water,  it  pulls  down  the  balloon  with 
its  weight  of  380  pounds.  It  seems  to  be  equivalent,  there- 
fore, to  about  620  pounds  of  ballast.  When  immersed  a 
little  over  six  feet  —  the  upper  four  feet  being  out  of  the 
water  —  it  exerts  neither  lifting  nor  depressing  effect. 
The  amount  of  either  may  be  perfectly  adjusted  between 
the  limits  stated  by  varying  the  immersion. 

In  the  Wellman-Vaniman  equilibrator  attached  to  the 
balloon  America,  which  last  year  carried  six  men  (and  a  cat) 
a  thousand  miles  in  three  days  over  the  Atlantic  Ocean,  a 
string  of  tanks  partly  filled  with  fuel  was  used  in  place  of 
the  timber  block.  As  the  tanks  were  emptied,  the  degree 
of  control  was  increased;  and  this  should  apparently 
have  given  ideal  results,  equilibration  being  augmented  as 
the  gas  supply  was  lost  by  leakage:  but  the  unsailorlike 
disregard  of  conditions  resulting  from  the  strains  trans- 
ferred from  a  choppy  sea  to  the  delicate  gas  bag  led  to 
disaster,  and  it  is  doubtful  whether  this  method  of  control 
can  ever  be  made  practicable.  The  America's  trip  was 
largely  one  of  a  drifting  rather  than  of  a  dirigible  balloon. 
The  equilibrator  could  be  used  only  in  flights  over  water 
in  any  case :  and  if  we  are  to  look  to  water  for  our  buoyancy, 
why  not  look  wholly  to  water  and  build  a  ship  instead 
of  a  balloon? 


DIRIGIBLE  BALLOONS  AND   OTHER  KINDS 


SHAPES 

THE  cylindrical  Zeppelin  balloon  with  approximately 
conical  ends  has  already  been  shown  (page  68).  Those 
balloons  in  which  the  shape  is  maintained  by  internal 


HENRY  GIFFARD'S  DIRIGIBLE 
(The  first  with  steam  power) 
s 

pressure  of  air  are  usually  pisciform,  that  is,  fish-shaped. 
Studies  have  actually  been  made  of  the  contour  lines  of 
various  fishes  and  equivalent  symmetrical  forms  derived, 

71 


Flying  Machines  Today 


the  outline  of    the    balloon  being    formed  by  a  pair  of 
approximately  parabolic  curves. 

The  first  flight  in  a  power  driven  balloon  was  made  by 
Giffard  in  1852.  This  balloon  had  an  independent  speed 
of  about  ten  feet  per  second,  but  was  without  appliances 


DIRIGIBLE  or  DUPUY  DE  LOME 
(Man  Power) 

for  steering.  A  ballonetted  balloon  of  120,000  cubic  feet 
capacity  was  directed  by  man  power  in  1872:  eight  men 
turned  a  screw  thirty  feet  in  diameter  which  gave  a  speed 
of  about  seven  miles  per  hour.  Electric  motors  and 
storage  batteries  were  used  for  dirigible  balloons  in  1883- 
'84:  in  the  latter  year,  Renard  and  Krebs  built  the  first 


Dirigible  Balloons  and  Other  Kinds 


73 


TISSANDIER  BROTHERS'   DIRIGIBLE  BALLOON 
(Electric  Motor) 

fish-shaped  balloon.  The  first  dirigible  driven  by  an 
internal  combustion  motor  was  used  by  Santos-Dumont 
in  1901. 

DIMENSIONS 

The  displacements  of  present  dirigibles  vary  from  20,000 
cubic  feet  (in  the  United  States  Signal  Corps  airship)  up 
to  460,000  cubic  feet  (in  the  Zeppelin) .  The  former  balloon 
has  a  carrying  capacity  only  about  equivalent  to  that  of 
a  Wright  biplane.  While  anchored  or  drifting  balloons 
are  usually  spherical,  all  dirigibles  are  elongated,  with  a 
length  of  from  four  to  eleven  diameters.  The  Zeppelin 
represents  an  extreme  elongation,  the  length  being  450 
feet  and  the  diameter  forty-two  feet.  At  the  other  extreme, 


74  Flying  Machines  Today 

some  of  the  English  military  dirigibles  are  thirty-one  feet 
in  diameter  and  only  112  feet  long.  Ballonet  capacities 
may  run  up  to  one-fifth  the  gas  volume.  All  present 
dirigibles  have  gasoline  engines  driving  propellers  from 


THE  BALDWIN 
Dirigible  of  the  United  States  Signal  Corps 

eight  to  twenty  feet  in  diameter.  The  larger  propellers 
are  connected  with  the  motors  by  gearing,  and  make  from 
250  to  700  turns  per  minute.  The  smaller  propellers  are 
direct  connected  and  make  about  1200  revolutions.  Speeds 
are  usually  from  fifteen  to  thirty  miles  per  hour. 

The  present-day  elongated  shape  is  the  result  of  the  effort 


Dirigible  Balloons  and  Other  Kinds 


75 


76  Flying  Machines  Today 

to  decrease  the  proportion  of  propulsion  resistance  due  to 
the  pressure  of  the  air  against  the  head  of  the  balloon. 
This  has  led  also  to  the  pointed  ends  now  universal;  and  to 
avoid  eddy  resistance  about  the  rear  it  is  just  as  important 
to  point  the  stern  as  the  bow.  As  far  as  head  end  resistance 
alone  is  concerned,  the  longer  the  balloon  the  better:  but 
the  friction  of  the  air  along  the  side  of  the  envelope  also 
produces  resistance,  so  that  the  balloon  must  not  be  too 
much  elongated.  Excessive  elongation  also  produces 
structural  weakness.  From  the  standpoint  of  stress  on  the 
fabric  of  the  envelope,  the  greatest  strain  is  that  which 
tends  to  break  the  material  along  a  longitudinal  line,  and 
this  is  true  no  matter  what  the  length,  as  long  as  the  seams 
are  equally  strong  in  both  directions  and  the  load  is  so 
suspended  as  not  to  produce  excessive  bending  strain  on 
the  whole  balloon.  In  the  Patric  (page  77),  some  dis- 
tortion due  to  loading  is  apparent.  The  stress  per  lineal 
inch  of  fabric  is  obtained  by  multiplying  the  net  pressure 
by  half  the  diameter  of  the  envelope  (in  inches). 

Ample  steering  power  (provided  by  vertical  planes,  as 
in  heavier-than-air  machines)  is  absolutely  necessary  in 
dirigibles:  else  the  head  could  not  be  held  up  to  the  wind 
and  the  propelling  machinery  would  become  ineffective. 

FABRICS 

The  material  for  the  envelope  and  ballonets  should  be 
light,  strong,  unaffected  by  moisture  or  the  atmosphere, 
non-cracking,  non-stretching,  and  not  acted  upon  by  varia- 


78  Flying  Machines  Today 

tions  in  temperature.  The  same  specifications  apply  to 
the  material  for  the  wings  of  an  aeroplane.  In  addition, 
for  use  in  dirigible  balloons,  fabrics  must  be  impermeable, 
resistent  to  chemical  action  of  the  gas,  and  not  subject  to 
spontaneous  combustion.  The  materials  used  are  vulcan- 
ized silk,  gold  beater's  skin,  Japanese  silk  and  rubber,  and 
cotton  and  rubber  compositions.  In  many  French  balloons, 
a  middle  layer  of  rubber  has  layers  of  cotton  on  each  side, 
the  whole  thickness  being  the  two  hundred  and  fiftieth 
part  of  an  inch.  In  the  Patrie,  this  was  supplemented  by 
an  outside  non-heat-absorbent  layer  of  lead  chromate  and 
an  inside  coating  of  rubber,  all  rubber  being  vulcanized. 
The  inner  rubber  layer  was  intended  to  protect  the  fabric 
against  the  destructive  action  of  impurities  in  the  gas. 

Fabrics  are  obtainable  in  various  colors,  painted,  var- 
nished, or  wholly  uncoated.  The  rubber  and  cotton  mix- 
tures are  regularly  woven  in  France  and  Germany  for 
aeroplanes  and  balloons.  The  cars  and  machinery  are 
frequently  shielded  by  a  fabricated  wall.  Weights  of 
envelope  materials  range  from  one  twenty-third  to  one- 
fourteenth  pound  per  square  foot,  and  breaking  stresses 
from  twenty-eight  to  one  hundred  and  thirty  pounds. 
Pressures  (net)  in  the  main  envelope  are  from  three-fifths 
to  one  and  a  quarter  ounces  per  square  inch,  those  in  the 
ballonets  being  somewhat  less.  The  Patrie  of  1907  had  an 
envelope  guaranteed  not  to  allow  the  leakage  of  more 
than  half  a  cubic  inch  of  hydrogen  per  square  foot  of  sur- 
face per  twenty-four  hours. 


Dirigible  Balloons  and  Other  Kinds  81 

The  best  method  of  cutting  the  fabric  is  to  arrange  for 
building  up  the  envelope  by  a  series  of  strips  about  the  cir- 
cumference, the  seams  being  at  the  bottom.  The  two 
warps  of  the  cloth  should  cross  at  an  angle  so  as  to  localize 
a  rip  or  tear.  Bands  of  cloth  are  usually  pasted  over  the 
seams,  inside  and  out,  with  a  rubber  solution;  this  is  to 
prevent  leakage  at  the  stitches. 

FRAMING 

In  the  Zeppelin,  the  rigid  aluminum  frame  is  braced 
every  forty-five  feet  by  transverse  diametral  rods  which 
make  the  cross-sections  resemble  a  bicycle  wheel  (page  68) . 
This  cross-section  is  not  circular,  but  sixteen-sided.  The 
pressure  is  resisted  by  the  framework  itself,  the  envelope 
being  required  to  be  impervious  only.  The  seventeen  com- 
partments are  separated  by  partitions  of  sheet  aluminum. 
There  is  a  system  of  complete  longitudinal  bracing  between 
these  partitions.  Under  the  main  framework,  the  cars  and 
machinery  are  carried  by  a  truss  about  six  feet  deep  which 
runs  the  entire  length.  The  cars  are  boat-shaped,  twenty 
feet  long  and  six  feet  wide,  three  and  one-half  feet  high, 
enclosed  in  aluminum  sheathing.  These  cars,  placed  about 
one  hundred  feet  from  the  ends,  are  for  the  operating  force 
and  machinery.  The  third  car,  carrying  passengers,  is 
built  into  the  keel. 

In  non-rigid  balloons  like  the  Patrie,  the  connecting 
frame  must  be  carefully  attached  to  the  envelope.  In  this 
particular  machine,  cloth  flaps  were  sewed  to  the  bag,  and 


Dirigible  Balloons  and  Other  Kinds  83 

nickel  steel  tubes  then  laced  in  the  flaps.  With  these 
tubes  as  a  base,  a  light  framework  of  tubes  and  wires, 
covered  with  a  laced-on  waterproof  cloth,  was  built  up  for 
supporting  the  load.  Braces  ran  between  the  various 
stabilizing  and  controlling  surfaces  and  the  gas  bag;  these 
were  for  the  most  part  very  fine  wire  cables.  The  weight 
of  the  car  was  concentrated  on  about  seventy  feet  of  the 
total  length  of  200  feet.  This  accounts  for  the  deformation 
of  the  envelope  shown  in  the  illustration  (page  77).  The 
frame  and  car  of  this  balloon  were  readily  dismantled  for 
transportation. 

In  some  of  the  English  dirigibles  the  cars  were  suspended 
by  network  passing  over  the  top  of  the  balloon. 

KEEPING  THE  KEEL  HORIZONTAL 

In  the  Zeppelin,  a  sliding  weight  could  be  moved  along 
the  keel  so  as  to  cause  the  center  of  gravity  to  coincide  with 
the  center  of  upward  pressure  in  spite  of  variations  in 
weight  and  position  of  gas,  fuel,  and  ballast.  In  the  Ger- 
man balloon  Parseval,  the  car  itself  was  movable  on  a 
longitudinal  suspending  cable  which  carried  supporting 
sheaves.  This  balloon  has  figured  in  recent  press  notices. 
It  was  somewhat  damaged  by  a  collision  with  its  shed  in 
March:  the  sixteen  passengers  escaped  unharmed.  A  few 
days  later,  emergency  deflation  by  the  rip-strip  was  made 
necessary  during  a  severe  storm.  In  the  ordinary  non-rigid 
balloon,  the  pumping  of  air  between  the  ballonets  aids  in 
controlling  longitudinal  equilibrium.  The  pump  may  be 


Dirigible  Balloons  and  Other  Kinds  85 

arranged  for  either  hand  or  motor  operation:  that  in  the 
Clement-Bayard  had  a  capacity  of  1800  liters  per  minute 
against  the  pressure  of  a  little  over  three-fifths  of  an  ounce. 
The  Parseval  has  two  ballonets.  Into  the  rear  of  these  air 
is  pumped  at  starting.  This  raises  the  bow  and  facilitates 
ascent  on  the  principle  of  the  inclined  surface  of  an  aero- 
plane. After  some  elevation  is  attained,  the  forward  bal- 
lonet  is  also  filled. 

STABILITY 

Besides  proper  distribution  of  the  loads,  correct  vertical 
location  of  the  propeller  is  important  if  the  balloon  is  to 
travel  on  a  level  keel.  In  some  early  balloons,  two  envel- 
opes side  by  side  had  the  propeller  at  the  height  of  the  axes 
of  the  gas  bags  and  midway  between  them.  The  modern 
forms  carry  the  car,  motor,  and  propeller  below  the  balloon 
proper.  The  air  resistance  is  mostly  that  of  the  bow  of  the 
envelope :  but  there  is  some  resistance  due  to  the  car,  and 
the  propeller  shaft  should  properly  be  at  the  equivalent 
center  of  all  resistance,  which  will  be  between  car  and  axis 
of  gas  bag  and  nearer  the  latter  than  the  former.  With  a 
single  envelope  and  propeller,  this  arrangement  is  imprac- 
ticable. By  using  four  (or  even  two)  propellers,  as  in  the 
Zeppelin  machine  (page  68),  it  can  be  accomplished.  If 
only  one  propeller  is  employed,  horizontal  rudder  planes 
must  be  disposed  at  such  angles  and  in  such  positions  as  to 
compensate  for  the  improper  position  of  the  tractive  force. 
Even  on  the  Zeppelin,  such  planes  were  employed  with 
advantage  (pages  66  and  73). 


86 


Flying  Machines  Today 


Perfect  stability  also  involves  freedom  from  rolling. 
This  is  usually  inherent  in  a  balloon,  because  the  center  of 
mass  is  well  below  the  center  of  buoyancy :  but  in  machines 
of  the  non-rigid  type  the  absence  of  a  ballonet  might  lead 


STERN  VIEW  OF  THE  ZEPPELIN 

to  both  rolling  and  pitching  when  the  gas  was  partially 
exhausted. 

What  is  called  " route  stability"  describes  the  condition 
of  straight  flight.  The  balloon  must  point  directly  in  its 
(independent)  course.  This  involves  the  use  of  a  steering 


Dirigible  Balloons  and  Other  Kinds  87 

rudder,  and,  in  addition,  of  fixed  vertical  planes,  which,  on 
the  principle  of  the  vertical  partitions  of  Voisin,  probably 
give  some  automatic  steadiness  to  the  course.  To  avoid 
the  difficulty  or  impossibility  of  holding  the  head  up  to 
the  wind  at  high  speeds,  an  empennage  or  feathering  tail 


THE  "CLEMENT-BAYARD" 

is  a  feature  of  all  present  balloons.  The  empennage  of  the 
Patrie  (page  77)  consisted  of  pairs  of  vertical  and  horizon- 
tal planes  at  the  extreme  stern.  In  the  France,  thirty-two 
feet  in  maximum  diameter  and  nearly  200  feet  long,  em- 
pennage planes  aggregating  about  400  square  feet  were 
placed  somewhat  forward  of  the  stern.  In  the  Clement- 


t   * 


Dirigible  Balloons  and  Other  Kinds  89 

Bayard,  the  empennage  consisted  of  cylindro-conical  bal- 
lonets  projecting  aft  from  the  stern.  A  rather  peculiar 
grouping  of  such  ballonets  was  used  about  the  prolonged 
stern  of  the  Ville  de  Paris. 

RUDDERS  AND  PLANES 

The  dirigible  has  thus  several  air-resisting  or  gliding 
surfaces.     The  approximately  "horizontal"  (actually  some- 


CAR    OF    THE    "LlBERTE: 


what  inclined)  planes  permit  of  considerable  ascent  and 
descent  by  the  expenditure  of  power  rather  than  gas,  and 
thus  somewhat  influence  the  problem  of  altitude  control. 
Each  of  the  four  sets  of  horizontal  rudder  planes  on  the 
Zeppelin,  for  example,  has,  at  thirty-five  miles  per  hour, 


go  Flying  Machines  Today 

with  an  inclination  equal  to  one-sixth  a  right  angle,  a 
lifting  power  of  nearly  a  ton;  about  equal  to  that  of  all 
of  the  gas  in  one  of  the  sixteen  compartments. 

Movable  rudders  may  be  either  hand  or  motor-operated. 
The  double  vertical  steering  rudder  of  the  Ville  de  Paris 
had  an  area  of  150  square  feet.  The  horizontally  pivoted 
rudders  for  vertical  direction  had  an  area  of  130  square 

feet. 

ARRANGEMENT  AND  ACCESSORIES 

The  motor  in  the  Ville  de  Paris  was  at  the  front  of  the 
car,  the  operator  behind  it.  This  car  had  the  excessive 
weight  of  nearly  700  pounds.  The  Patrie  employed  a  non- 
combustible  shield  over  the  motor,  for  the  protection  of  the 
envelope:  its  steering  wheel  was  in  front  and  the  motor 
about  in  the  middle  of  the  car.  The  gasoline  tank  was 
under  the  car,  compressed  air  being  used  to  force  the 
fuel  up  to  the  motor,  which  discharged  its  exhaust  down- 
ward at  the  rear  through  a  spark  arrester.  Motors  have 
battery  and  magneto  ignition  and  decompression  cocks, 
and  are  often  carried  on  a  spring-supported  chassis.  The 
interesting  Parseval  propeller  has  four  cloth  blades  which 
hang  limp  when  not  revolving.  When  the  motor  is  run- 
ning, these  blades,  which  are  weighted  with  lead  at  the 
proper  points,  assume  the  desired  form. 

Balloons  usually  carry  guide  ropes  at  head  and  stern, 
the  aggregate  weight  of  which  may  easily  exceed  a  hundred 
pounds.  In  descending,  the  bow  rope  is  first  made  fast, 
and  the  airship  then  stands  with  its  head  to  the  wind,  to  be 


Dirigible  Balloons  and  Other  Kinds  91 

hauled  in  by  the  stern  rope.  For  the  large  French  military 
balloons,  this  requires  a  force  of  about  thirty  men.  The 
Zeppelin  descends  in  water,  being  lowered  until  the  cars 
float,  when  it  is  docked  like  a  ship  (see  page  84).  Land- 
ing skids  are  sometimes  used,  as  with  aeroplanes. 

The  balloon  must  have  escape  valves  in  the  main  envelope 
and  ballonets.  In  addition  it  has  a  "rip-strip"  at  the  bot- 
tom by  which  a  large  cut  can  be  made  and  the  gas  quickly 
vented  for  the  purpose  of  an  emergency  descent.  Common 
equipment  includes  a  siren,  megaphone,  anchor  pins,  fire 
extinguisher,  acetylene  search  light,  telephotographic  appa- 
ratus, registering  and  indicating  gages  and  other  instru- 
ments, anemometer,  possibly  carrier  pigeons;  besides  fuel, 
oil  and  water  for  the  motor,  and  the  necessary  supplies  for 
the  crew.  The  glycerine  floated  compass  of  Moisant  must 
now  also  be  included  if  we  are  to  contemplate  genuine 
navigation  without  constant  recourse  to  landmarks. 

AMATEUR  DIRIGIBLES 

The  French  Zodiac  types  of  " aerial  runabout''  displace 
700  cubic  meters,  carrying  one  passenger  with  coal  gas  or 
two  passengers  with  a  mixture  of  coal  gas  and  hydrogen. 
The  motor  is  four-cylinder,  sixteen  horse-power,  water- 
cooled.  The  stern  screw,  of  seven  feet  diameter,  makes 
600  turns  per  minute,  giving  an  independent  speed  of 
nineteen  miles  per  hour.  The  machine  can  remain  aloft 
three  hours  with  165  pounds  of  supplies.  It  costs  $5000. 
Hydrogen  costs  not  far  from  a  cent  per  cubic  foot  (twenty 


9  2  Flying  Machines  Today 


THE  ZODIAC  No.  2 
May  be  deflated  and  easily  transported 

cents  per  cubic  meter)  so  that  the  question  of  gas  leakage 
may  be  at  least  as  important  as  the  tire  question  with 
automobiles. 

THE  FORT  OMAHA  PLANT 

The  Signal  Corps  post  at  Fort  Omaha  has  a  plant  com- 
prising a  steel  balloon  house  of  size  sufficient  to  house  one 
of  the  largest  dirigibles  built,  an  electrolytic  plant  for 
generating  hydrogen  gas,  having  a  capacity  of  3000  cubic 
feet  per  hour,  a  50,000  cubic  foot  gas  storage  tank,  and 
the  compressing  and  carrying  equipment  involved  in  pre- 
paring gas  for  shipment  at  high  pressure  in  steel  cylinders. 


Dirigible  Balloons  and  Other  Kinds 


93 


94  Flying  Machines  Today 

BALLOON  PROGRESS 

The  first  aerial  buoy  of  Montgolfier  brothers,  in  1783, 
led  to  the  suggestion  of  Meussier  that  two  envelopes  be 
used;  the  inner  of  an  impervious  material  to  prevent  gas 
leakage,  and  the  outer  for  strength.  There  was  perhaps 


THE  "CAROLINE"  OF  ROBERT  BROTHERS,  1784 
The  ascent  terminated  tragically 

a  foreshadowing  of  the  Zeppelin  idea.  Captive  and  drift- 
ing balloons  were  used  during  the  wars  of  the  French 
Revolution:  they  became  a  part  of  standard  equipment 
in  our  own  War  of  Secession  and  in  the  Franco-Prussian 
conflict.  The  years  1906  to  1908  recorded  rapid  progress 
in  the  development  of  the  dirigible:  the  record-breaking 
Zeppelin  trip  was  in  1909  and  Wellman's  America  exploit 


Dirigible  Balloons  and  Other  Kinds 


95 


THE  ASCENT  AT  VERSAILLES,  1783 
The  first  balloon  carrying  living  beings  in  the  air 


g6  Flying  Machines  Today 

in  October,  1910.  Unfortunately,  dirigibles  have  had  a 
a  bad  record  for  stanchness:  the  Patrie,  Republique, 
Zeppelin  (I  and  II) ,  Deutschland,  Clement-Bayard  —  all 
have  gone  to  that  bourne  whence  no  balloon  returns. 


SOUSCRIPTION 

de  2OO  Billets  <le  50  Francs 

a  arnt  alacft  t/tr/is  /«  iHurltr  et  lan^uit  ni  inxuit  ilruj:  liinilt't*  .ni*iM-inli, 
..f      ..  ' 


•'/.,  rr.M-  nmfrm  (;>  <t',jn;,er  ,-f  <lej>f:,>  ,,un,,,/ 1,:  „„;/„•', /.„..,-  I,  ,  !.,'„. 

Ill  .\nnwif  ,-Jir-y.  M  /  < .'//,•/ w/w  ,/  /„  /!„,/•  , 


Investors  were  lacking  to  bring  about  the  realization  of  this  project 

It  is  gratifying  to  record  that  Count  Zeppelin's  latest 
machine,  the  Deutschland  II,  is  now  in  operation.  During 
the  present  month  (April,  1911),  flights  have  been  made 
covering  90  miles  and  upward  at  speeds  exceeding  20  miles 


98  Flying  Machines  Today 

per  hour  with  the  wind  unfavorable.  This  balloon  is  in- 
tended for  use  as  a  passenger  excursion  vehicle  during  the 
coming  summer,  under  contract  with  the  municipality  of 
Dusseldorf. 

At  the  present  moment,  Neale,  in  England,  is  reported 
to  be  building  a  dirigible  for  a  speed  of  a  hundred  miles  per 
hour.  The  Siemens-Schuckart  non-rigid  machine,  nearly 
400  feet  long  and  of  500  horse-power,  is  being  tried  out  at 
Berlin:  it  is  said  to  carry  fifty  passengers.*  Fabrice,  of 
Munich,  is  experimenting  with  the  Inchard,  with  a  view  to 
crossing  the  Atlantic  at  an  early  date.  Mr.  Vaniman, 
partner  of  Wellman  on  the  America  expedition,  is  planning 
a  new  dirigible  which  it  is  proposed  to  fly  across  the  ocean 
before  July  4.  The  engine,  according  to  press  reports, 
will  develop  200  horse-power,  and  the  envelope  will  be 
more  elongated  than  that  of  the  America.  And  meanwhile 
a  Chicago  despatch  describes  a  projected  fifty-passenger 
machine,  to  have  a  gross  lifting  power  of  twenty-five  tons ! 
Germany  has  a  slight  lead  in  number  of  dirigible  balloons 
-sixteen  in  commission  and  ten  building.  France  fol- 
lows closely  with  fourteen  active  and  eleven  authorized. 
This  accounts  for  two-thirds  of  all  the  dirigible  balloons  in 
the  world.  Great  Britain,  Italy,  and  Russia  rank  in  the 
order  named.  The  United  States  has  one  balloon  of  the 
smallest  size.  Spain  has,  or  had,  one  dirigible.  As  to 

*  According  to  press  reports,  temporary  water  ballast  will  be  taken  on 
during  the  daytime,  to  offset  the  ascensional  effect  of  the  hot  sun  on  the 
envelope. 


Dirigible  Balloons  and  Other  Kinds 


99 


THE  FIRST  FLIGHT  FOR  THE  GORDON-BENNET  CUP. 
Won  by  Lieut.  Frank  P.  Lahm,  U.S.A.,  1906.     Figures  on  the  map  de- 
note distances  in  kilometers.     The  cup  has  been  offered  annually  by  Mr. 
James  Gordon-Bennet  for  international  competition  under  such  conditions 
as  may  be  prescribed  by  the  International  Aeronautic  Federation. 


ioo  Flying  Machines  Today 

aeroplanes,  however,  the  United  States  and  England  rank 
equally,  having  each  about  one-fourth  as  many  machines 
as  France  (which  seems,  therefore,  to  maintain  a  "  four- 
power  standard")-  Germany,  Russia,  and  Italy  follow, 
in  order,  the  United  States.  These  figures  include  all 
machines,  whether  privately  or  nationally  owned.  Until 
lately,  our  own  government  operated  but  one  aeroplane. 
A  recent  appropriation  by  Congress  of  $125,000  has  led  to,- 
arrangements  for  the  purchase  of  a  few  additional  bi- 
planes of  the  Wright  and  Curtiss  types;  and  a  training 
school  for  army  officers  has  been  regularly  conducted  at 
San  Diego,  CaL,  during  the  past  winter.  The  Curtiss 
machine  to  be  purchased  is  said  to  carry  700  pounds  of 
dead  weight  with  a  sail  area  of  500  square  feet.  It  is 
completely  demountable  and  equipped  with  pontoons. 


THE  QUESTION  OF  POWER 

IN  the  year  1810,  a  steam  engine  weighed  something 
over  a  ton  to  the  horse-power.  This  was  reduced  to  about 
200  pounds  in  1880.  The  steam-driven  dirigible  balloon 
of  Giffard,  in  1852,  carried  a  complete  power  plant  weigh- 
ing a  little  over  100  pounds  per  horse -power;  about  the 
weight  of  a  modern  locomotive.  The  unsuccessful  Maxim 
flying  machine  of  1894  brought  this  weight  down  to  less 
than  20  pounds.  The  gasoline  engine  on  the  original 
Wright  machines  weighed  about  5  pounds  to  the  horse- 
power; those  on  some  recent  French  machines  not  far 
from  2  pounds. 

Pig  iron  is  worth  perhaps  a  cent  a  pound.  An  ordinary 
steam  or  gas  engine  may  cost  eight  cents  a  pound;  a  steam 
turbine,  perhaps  forty  cents.  A  high  grade  automobile 
or  a  piano  may  sell  for  a  dollar  a  pound;  the  Gnome  aero- 
plane motor  is  priced  at  about  twenty  dollars  a  pound. 
This  is  considerably  more  than  the  price  of  silver.  The 
motor  and  accessories  account  for  from  two-thirds  to  nine- 
tenths  of  the  total  cost  of  an  aeroplane. 

A  man  weighing  150  pounds  can  develop  at  the  outside 
about  one-eighth  of  a  horse-power.  It  would  require 
1 200  pounds  of  man  to  exert  one  horse-power.  Consid- 
ered as  an  engine,  then,  a  man  is  (weight  for  weight)  only 


101 


IO2  Flying  Machines  Today 

one  six-hundredth  as  effective  as  a  Gnome  motor.  In  the 
original  Wright  aeroplane,  a  weight  of  half  a  ton  was 
sustained  at  the  expenditure  of  about  twenty-five  horse- 
power. The  motor  weight  was  about  one-eighth  of  the 
total  weight.  If  traction  had  been  produced  by  man-power, 


THE  GNOME  MOTOR 
(Aeromotion  Company  of  America) 

30,000  pounds  of  man  would  have  been  necessary:  thirty 
times  the  whole  weight  supported. 

Under  the  most  favorable  conditions,  to  support  his 
own  weight  of  150  pounds  (at  very  high  gliding  velocity 
and  a  slight  angle  of  inclination,  disregarding  the  weight 
of  sails  necessary),  a  man  would  need  to  have  the  strength 


The  Question  of  Power  103 

of  about  fifteen  men.  No  such  thing  as  an  aerial  bicycle, 
therefore,  appears  possible.  The  man  can  not  emulate 
the  bird. 


u 

! 


i] 


The  power  plant  of  an  air  craft  includes  motor,  water 
and  water  tank,  radiator  and  piping,  shaft  and  bearings, 


104 


Flying  Machines  Today 


propeller,  controlling  wheels  and  levers,  carbureter,  fuel, 
lubricating  oil  and  tanks  therefor.  Some  of  the  weight  may 
eventually  be  eliminated  by  employing  a  two-cycle  motor 
(which  gives  more  power  for  its  size)  or  by  using  rotary 
air-cooled  cylinders.  Propellers  are  made  light  by  employ- 
ing wood  or  skeleton  construction.  One  eight-foot  screw  of 


ONE  OF  THE  MOTORS  or  THE  ZEPPELIN 

white  oak  and  spruce,  weighing  from  twelve  to  sixteen 
pounds,  is  claimed  to  give  over  400  pounds  of  propelling 
force  at  a  thousand  turns  per  minute. 

The  cut  shows  the  action  of  the  so-called  " four-cycle" 
motor.  Four  strokes  are  required  to  produce  an  impulse 
on  the  piston  and  return  the  parts  to  their  original  posi- 


The  Question  oj  Power 


ACTION  OF  THE  FOUR-CYCLE  ENGINE 


io6 


Flying  Machines  Today 


tions.  On  the  first,  or  suction  stroke,  the  combustible 
mixture  is  drawn  into  the  cylinder,  the  inlet  valve  being 
open  and  the  outlet  valve  closed.  On  the  second  stroke, 
both  valves  are  closed  and  the  mixture  is  highly  compressed. 
At  about  the  end  of  this  stroke,  a  spark  ignites  the  charge, 
a  still  greater  pressure  is  produced  in  consequence,  and  the 
energy  of  the  gas  now  forces  the  piston  outward  on  its 
third  or  " working"  stroke,  the  valves  remaining  closed. 
Finally,  the  outlet  valve  is  opened  and  a  fourth  stroke 
sweeps  the  burnt  gas  out  of  the  cylinder. 


In  the  " two-cycle"  engine,  the  piston  first  moves  to 
the  left,  compressing  a  charge  already  present  in  the  cylin- 
der at  F,  and  meanwhile  drawing  a  fresh  supply  through 
the  valve  A  and  passages  C  to  the  space  D.  On  the 
return  stroke,  the  exploded  gas  in  F  expands,  doing  its 


The  Question  of  Power  107 

work,  while  that  in  D  is  slightly  compressed,  the  valve  A 
being  now  closed.  When  the  piston,  moving  toward  the 
right,  opens  the  passage  E,  the  burnt  gas  rushes  out.  A 
little  later,  when  the  passage  /  is  exposed,  the  fresh  com- 
pressed gas  in  D  rushes  through  C,  B,  and  7  to  F.  The  oper- 
ation may  now  be  repeated.  Only  two  strokes  have  been 
necessary.  The  cylinder  develops  power  twice  as  rapidly 
as  before:  but  at  the  cost  of  some  waste  of  gas,  since  the 
inlet  (7)  and  outlet  (E)  passages  are  for  a  brief  interval 
both  open  at  once:  a  condition  not  altogether  remedied  by 
the  use  of  a  deflector  at  G.  A  two-cycle  cylinder  should 
give  nearly  twice  the  power  of  a  four-cycle  cylinder  of  the 
same  size,  and  the  two-cycle  engine  should  weigh  less, 
per  horse-power;  but  it  requires  from  10  to  30%  more 
fuel,  and  fuel  also  counts  in  the  total  weight. 

The  high  temperatures  in  the  cylinder  would  soon  make 
the  cast-iron  walls  red-hot,  unless  the  latter  were  artifi- 
cially cooled.  The  usual  method  of  cooling  is  to  make 
the  walls  hollow  and  circulate  water  through  them.  This 
involves  a  pump,  a  quantity  of  water,  and  a  "radiator" 
(cooling  machine)  so  that  the  water  can  be  used  over  and 
over  again.  To  cool  by  air  blowing  over  the  surface  of 
the  cylinder  is  relatively  ineffective:  but  has  been  made 
possible  in  automobiles  by  building  fins  on  the  cylinders 
so  as  to  increase  the  amount  of  cooling  surface.  When  the 
motors  are  worked  at  high  capacity,  or  when  two-cycle 
motors  are  used,  the  heat  is  generated  so  rapidly  that  this 
method  of  cooling  is  regarded  as  inapplicable.  By  rapidly 


io8  Flying  Machines  Today 

rotating  the  cylinders  themselves  through  the  air,  as  in 
motors  like  the  Gnome,  air  cooling  is  made  sufficiently 
adequate,  but  the  expenditure  of  power  in  producing  this 
rotation  has  perhaps  not  been  sufficiently  regarded. 


MOTOR  AND  PROPELLER 
(Detroit  Aeronautic  Construction  Co.) 

Possible  progress  in  weight  economy  is  destined  to  be 
limited  by  the  necessity  for  reserve  motor  equipment. 

The  engine  used  is  usually  the  four-cycle,  single-acting, 
four-cylinder  gasoline  motor  of  the  automobile,  designed 


The  Question  of  Power  109 

for  great  lightness.  The  power  from  each  cylinder  of 
such  a  motor  is  approximately  that  obtained  by  dividing 
the  square  of  the  diameter  in  inches  by  the  figure  i\. 
Thus  a  five-inch  cylinder  should  give  ten  horse-power 
-  at  normal  piston  speed.  On  account  of  friction  losses 
and  the  wastefulness  of  a  screw  propeller,  not  more  than 
half  this  power  is  actually  available  for  propulsion. 

The  whole  power  plant  of  the  Clement-Bayard  weighed 
about  eleven  pounds  to  the  horse-power.  This  balloon 
was  184  feet  long  and  35  feet  in  maximum  diameter, 
displacing  about  100,000  cubic  feet.  It  carried  six  pas- 
sengers, about  seventy  gallons  of  fuel,  four  gallons  of 
lubricating  oil,  fifteen  gallons  of  water,  600  pounds  of 
ballast,  and  130  pounds  of  ropes.  The  motor  developed 
100  horse-power  at  a  thousand  revolutions  per  minute. 
About  eight  gallons  of  fuel  and  one  gallon  of  oil  were  con- 
sumed per  hour  when  running  at  the  full  independent 
speed  of  thirty-seven  miles  per  hour. 

The  Wellman  balloon  America  is  said  to  have  consumed 
half  a  ton  of  gasoline  per  twenty-four  hours :  an  eight  days' 
supply  was  carried.  The  gas  leakage  in  this  balloon  was 
estimated  to  have  been  equivalent  to  a  loss  of  500  pounds 
of  lifting  power  per  day. 

The  largest  of  dirigibles,  the  Zeppelin,  had  two  motors 
of  170  horse-power  each.  It  made,  in  1909,  a  trip  of  over 
800  miles  in  thirty-eight  hours. 

The  engine  of  the  original  Voisin  cellular  biplanes  was 
an  eight-cylinder  Antoinette  of  fifty  horse-power,  set  near 


no 


Flying  Machines  Today 


TWO-CYLINDER  OPPOSED  ENGINE. 
(From  Aircraft) 


FOUR-CYLINDER  VERTICAL  ENGINE 
(THE  DEAN  MANUFACTURING  Co.) 


The  Question  of  Power  in 

the  rear  edge  of  the  lower  of  the  main  planes.  The 
Wright  motors  are  placed  near  the  front  edge.  A  twenty- 
five  horse  power  motor  at  1400  revolutions  propelled 
the  Fort  Myer  machine,  which  was  built  to  carry  two 
passengers,  with  fuel  for  a  125  mile  flight:  the  total 
weight  of  the  whole  flying  apparatus  being  about  half 
a  ton. 

The  eight-cylinder  Antoinette  motor  on  a  Farman  bi- 
plane, weighing  175  pounds,  developed  thirty-eight  horse- 
power at  1050  revolutions.  The  total  weight  of  the  ma- 
chine was  nearly  1200  pounds,  and  its  speed  twenty-eight 
miles  per  hour. 

The  eight-cylinder  Curtiss  motor  on  the  June  Bug  was 
air  cooled.  This  aeroplane  weighed  650  pounds  and  made 
thirty-nine  miles  per  hour,  the  engine  developing  twenty- 
five  horse-power  at  1200  turns. 

RESISTANCE  OF  AEROPLANES 

The  chart  on  page  24  (see  also  the  diagram  of  page 
23)  shows  that  the  lifting  power  of  an  aeroplane  increases 
as  the  angle  of  inclination  increases,  up  to  a  certain  limit. 
The  resistance  to  propulsion  also  increases,  however:  and 
the  ratio  of  lifting  power  to  resistance  is  greatest  at  a  very 
small  angle  —  about  five  or  six  degrees.  Since  the  motor 
power  and  weight  are  ruling  factors  in  design,  it  is  impor- 
tant to  fly  at  about  this  angle.  The  supporting  force  is 
then  about  two  pounds,  and  the  resistance  about  three- 
tenths  of  a  pound,  per  square  foot  of  sail  area,  if  the  veloc- 


ii2  Flying  Machines  Today 

ity  is  that  assumed  in  plotting  the  chart:  namely,  about 
fifty-five  miles  per  hour. 

But  the  resistance  R  indicated  on  pages  23  and  24  is  not 
the  only  resistance  to  propulsion.  In  addition,  we  have 
the  frictional  resistance  of  the  air  sliding  along  the  sail  sur- 
face. The  amount  of  this  resistance  is  independent  of  the 
angle  of  inclination:  it  depends  directly  upon  the  area  of 
the  planes,  and  in  an  indirect  way  on  their  dimensions  in 
the  direction  of  movement.  It  also  varies  nearly  with  the 
square  of  the  velocity.  At  any  velocity,  then,  the  addition 
of  this  frictional  resistance,  which  does  not  depend  on  the 
angle  of  inclination,  modifies  our  views  as  to  the  desirable 
angle:  and  the  total  resistance  reaches  a  minimum  (in  pro- 
portion to  the  weight  supported)  when  the  angle  is  about 
three  degrees  and  the  velocity  about  fifty  miles  per  hour. 

This  is  not  quite  the  best  condition,  however.  The  skin 
friction  does  not  vary  exactly  with  the  square  of  the  veloc- 
ity: and  when  the  true  law  of  variation  is  taken  into  ac- 
count, it  is  found  that  the  horse-power  is  a  minimum  at 
an  angle  of  about  five  degrees  and  a  speed  of  about  forty 
miles  per  hour.  The  weight  supported  per  horse-power 
may  then  be  theoretically  nearly  a  hundred  pounds :  and  the 
frictional  resistance  is  about  one-third  the  direct  pressure 
resistance.  This  must  be  regarded  as  the  approximate 
condition  of  best  effectiveness:  not  the  exact  condition, 
because  in  arriving  at  this  result  we  have  regarded  the 
sails  as  square  flat  planes  whereas  in  reality  they  are 
arched  and  of  rectangular  form. 


The  Question  of  Power  113 

At  the  most  effective  condition,  the  resistance  to  pro- 
pulsion is  only  about  one- tenth  the  weight  supported. 
Evidently  the  air  is  helping  the  motor. 

RESISTANCE  OF    DIRIGIBLES 

If  the  bow  of  a  balloon  were  cut  off  square,  its  head  end 
resistance  would  be  that  given  by  the  rule  already  cited 
(page  19):  one  three-hundredth  pound  per  square  foot, 


HEAD  END  SHAPES 

multiplied  by  the  square  of  the  velocity.  But  by  pointing 
the  bow  an  enormous  reduction  of  this  pressure  is  pos- 
sible. If  the  head  end  is  a  hemisphere  (as  in  the  English 
military  dirigible),  the  reduction  is  about  one- third.  If 
it  is  a  sharp  cone,  the  reduction  may  be  as  much  as  four- 
fifths.  Unless  the  stern  is  also  tapered,  however,  there 
will  be  a  considerable  eddy  resistance  at  that  point. 

If  head  end  resistance  were  the  only  consideration,  then 
for  a  balloon  of  given  diameter  and  end  shape  it  would  be 
independent  of  the  length  and  capacity.  The  longer  the 
balloon,  the  better.  Again,  since  the  volume  of  any  solid 
body  increases  more  rapidly  than  its  surface  (as  the  lin- 
ear dimensions  are  increased),  large  balloons  would  have 
a  distinct'  advantage  over  small  ones.  The  smallest 


ii4  Flying  Machines  Today 

dirigible  ever  built  was  that  of  Santos-Dumont,  of  about 
5000  cubic  feet. 

Large  balloons,  however,  are  structurally  weak:  and 
more  is  lost  by  the  extra  bracing  necessary  than  is  gained 
by  reduction  of  head  end  resistance.  It  is  probable  that 
the  Zeppelin  represents  the  limit  of  progress  in  this  direc- 
tion; and  even  in  that  balloon,  if  it  had  not  been  that  the 
adoption  of  a  rigid  type  necessitated  great  structural 
strength,  it  is  doubtful  if  as  great  a  length  would  have  been 
fixed  upon,  in  proportion  to  the  diameter. 

The  frictional  resistance  of  the  air  gliding  along  the  sur- 
face of  the  envelope,  moreover,  invalidates  any  too  arbi- 
trary conclusions.  This,  as  in  the  aeroplane,  varies  nearly 
as  the  square  of  the  velocity,  and  is  usually  considerably 
greater  than  the  direct  head  end  resistance.  Should  the 
steering  gear  break,  however,  and  the  wind  strike  the  side 
of  the  balloon,  the  pressure  of  the  wind  against  this  greatly 
increased  area  would  absolutely  deprive  it  of  dirigibility. 

A  stationary,  drifting,  or  " sailing"  balloon  may  as  well 
have  the  spherical  as  well  as  any  other  shape:  it  makes  the 
wind  a  friend  instead  of  a  foe  and  requires  nothing  in  the 
way  of  control  other  than  regulation  of  altitude. 

INDEPENDENT  SPEED  AND  TIME  TABLE 

The  air  pressure,  direct  and  frictional  resistances,  and 
power  depend  upon  the  relative  velocity  of  flying  machine 
and  air.  It  is  this  relative  velocity,  not  the  velocity  of 
the  balloon  as  compared  with  a  point  on  the  earth's  sur- 


n6  Flying  Machines  Today 

face,  that  marks  the  limit  of  progression.  Hence  the  speed 
of  the  wind  is  an  overwhelming  factor  to  be  reckoned  with 
in  developing  an  aerial  time  table.  If  we  wish  to  travel 
east  at  an  effective  speed  of  thirty  miles  per  hour,  while  the 
wind  is  blowing  due  west  at  a  speed  of  ten  miles,  our  ma- 
chine must  have  an  independent  speed  of  forty  miles. 
On  the  other  hand,  if  we  wish  to  travel  west,  an  independ- 
ent speed  of  twenty  miles  per  hour  will  answer. 

Again,  if  the  wind  is  blowing  north  at  thirty  miles  per 
hour,  and  the  minimum  (relative)  velocity  at  which  an 
aeroplane  will  sustain  its  load  is  forty  miles  per  hour,  we 
cannot  progress  northward  any  more  slowly  than  at  sev- 
enty miles'  speed.  And  we  have  this  peculiar  condition 
of  things:  suppose  the  wind  to  be  blowing  north  at  fifty 
miles  per  hour.  The  aeroplane  designed  for  a  forty  mile 
speed  may  then  face  this  wind  and  sustain  itself  while 
actually  moving  backward  at  an  absolute  speed  (as  seen 
from  the  earth)  of  ten  miles  per  hour. 

We  are  at  the  mercy  of  the  wind,  and  wind  velocities 
may  reach  a  hundred  miles  an  hour.  The  inherent  dis- 
advantage of  aerial  flight  is  in  what  engineers  call  its 
"low  load  factor."  That  is,  the  ratio  of  normal  perform- 
ance required  to  possible  abnormal  performance  necessary 
under  adverse  conditions  is  extremely  low.  To  make  a 
balloon  truly  dirigible  throughout  the  year  involves,  at 
Paris,  for  example,  as  we  have  seen,  a  speed  exceeding 
fifty-four  miles  per  hour:  and  even  then,  during  one- tenth 
the  year,  the  effective  speed  would  not  exceed  twenty  miles 


n8  Flying  Machines  Today 

per  hour.  A  time  table  which  required  a  schedule  speed 
reduction  of  60%  on  one  day  out  of  ten  would  be  obviously 
unsatisfactory. 

Further,  if  we  aim  at  excessively  high  independent 
speeds  for  our  dirigible  balloons,  in  order  to  become  inde- 
pendent of  wind  conditions,  we  soon  reach  velocities  at 
which  the  gas  bag  is  unnecessary:  that  is,  a  simple  wing 
surface  would  at  those  speeds  give  ample  support.  The 
increased  difficulty  of  maintaining  rigidity  of  the  envelope, 
and  of  steering,  at  the  great  pressures  which  would  accom- 
pany these  high  velocities  would  also  operate  against  the 
dirigible  type. 

With  the  aeroplane,  higher  speed  means  less  sail  area 
for  a  given  weight  and  a  stronger  machine.  Much  higher 
speeds  are  probable.  We  have  already  a  safe  margin  as 
to  weight  per  horse-power  of  motor,  and  many  aeroplane 
motors  are  for  stanchness  purposely  made  heavier  than 
they  absolutely  need  to  be. 

THE  COST  OF  SPEED 

Since  the  whole  resistance,  in  either  type  of  flying  ma- 
chine, is  approximately  proportional  to  the  square  of  the 
velocity;  and  since  horse-power  (work)  is  the  product  of 
resistance  and  velocity,  the  horse-power  of  an  air  craft 
of  any  sort  varies  about  as  the  cube  of  the  speed.  To 
increase  present  speeds  of  dirigible  balloons  from  thirty 
to  sixty  miles  per  hour  would  then  mean  eight  times  as 
much  horse-power,  eight  times  as  much  motor  weight, 


The  Question  of  Power  119 

eight  times  as  rapid  a  rate  of  fuel  consumption,  and  (since 
the  speed  has  been  doubled)  four  times  as  rapid  a  con- 
sumption of  fuel  in  proportion  to  the  distance  traveled. 
Either  the  radius  of  action  must  be  decreased,  or  the  weight 
of  fuel  carried  must  be  greatly  increased,  if  higher  veloc- 
ities are  to  be  attained.  Present  (independent)  aeroplane 
speeds  are  usually  about  fifty  miles  per  hour,  and  there  is 
not  the  necessity  for  a  great  increase  which  exists  with  the 
lighter-than-air  machines.  We  have  already  succeeded  in 
carrying  and  propelling  fifty  pounds  of  total  load  or  fifteen 
pounds  of  passenger  load  per  horse-power  of  motor,  with 
aeroplanes;  the  ratio  of  net  load  to  horse  power  in  the  diri- 
gible is  considerably  lower ;  but  the  question  of  weight  in 
relation  to  power  is  of  relatively  smaller  importance  in  the 
latter  machine,  where  support  is  afforded  by  the  gas  and 

not  by  the  engine. 

THE  PROPELLER 

Very  little  effort  has  been  made  to  utilize  paddle  wheels 
for  aerial  propulsion;  the  screw  is  almost  universally  em- 
ployed. Every  one  knows  that  when  a  bolt  turns  in  a 
stationary  nut,  it  moves  forward  a  distance  equal  to  the 
pitch  (lengthwise  distance  between  two  adjacent  threads) 
at  every  revolution.  A  screw  propeller  is  a  bolt  partly 
cut  away  for  lightness,  and  the  "nut"  in  which  it  works 
is  water  or  air.  It  does  not  move  forward  quite  as  much  as 
its  pitch,  at  each  revolution,  because  any  fluid  is  more  or 
less  slippery  as  compared  with  a  nut  of  solid  metal.  The 
difference  between  the  pitch  and  the  actual  forward  move- 


I2O  Flying  Machines  Today 

ment  of  the  vessel  at  each  revolution  is  called  the  "slip," 
or  "slip  ratio."  It  is  never  less  than  ten  or  twelve  per  cent 
in  marine  work,  and  with  aerial  screws  is  much  greater. 
Within  certain  limits,  the  less  the  slip,  the  greater  the 
efficiency  of  the  propeller.  Small  screws  have  relatively 
greater  slips  and  less  efficiency,  but  are  lighter.  The  maxi- 
mum efficiency  of  a  screw  propeller  in  water  is  under  80%. 
According  to  Langley's  experiments,  the  usual  efficiency  in 
air  is  only  about  50%.  This  means  that  only  half  the  power 
of  the  motor  will  be  actually  available  for  producing  for- 
ward movement  —  a  conclusion  already  foreshadowed. 

In  common  practice,  the  pitch  of  aerial  screws  is  not 
far  from  equal  to  the  diameter.  The  rate  of  forward  move- 
ment, if  there  were  no  slip,  would  be  proportional  to  the 
pitch  and  the  number  of  revolutions  per  minute.  If  the 
latter  be  increased,  the  former  may  be  decreased.  Screws 
direct-connected  to  the  motors  and  running  at  high  speeds 
will  therefore  be  of  smaller  pitch  and  diameter  than  those 
run  at  reduced  speed  by  gearing,  as  in  the  machine  illus- 
trated on  page  134.  The  number  of  blades  is  usually  two, 
although  this  gives  less  perfect  balance  than  would  a  larger 
number.  The  propeller  is  in  many  monoplanes  placed  in 
front:  this  interferes,  unfortunately,  with  the  air  currents 
against  the  supporting  surfaces. 

There  is  always  some  loss  of  power  in  the  bearings  and 
power-transmitting  devices  between  the  motor  and  pro- 
peller. This  may  decrease  the  power  usefully  exerted 
even  to  less  than  half  that  developed  by  the  motor. 


GETTING     UP     AND     DOWN:     MODELS     AND 
GLIDERS:    AEROPLANE    DETAILS 

LAUNCHING 

THE  Wright  machines  (at  least  in  their  original  form) 
have  usually  been  started  by  the  impetus  of  a  falling  weight, 
which  propels  them  along  skids  until  the  velocity  suffices 
to  produce  ascent.  The  preferred  designs  among  French 
machines  have  contemplated  self-starting  equipment. 


WRIGHT  BIPLANE  ON  STARTING  RAIL,  SHOWING  PYLON  AND  WEIGHT 

This  involves  mounting  the  machine  on  pneumatic-tired 
bicycle  wheels  so  that  it  can  run  along  the  ground.  If  a 
fairly  long  stretch  of  good,  wide,  straight  road  is  avail- 
able, it  is  usually  possible  to  ascend.  The  effect  of  alti- 
tude and  atmospheric  density  on  sustaining  power  is 
forcibly  illustrated  by  the  fact  that  at  Salt  Lake  City 
one  of  the  aviators  was  unable  to  rise  from  the  ground. 

To  accelerate  a  machine  from  rest  to  a  given  velocity 
in  a  given  time  or  distance  involves  the  use  of  propulsive 


121 


122 


Flying  Machines  Today 


Getting  Up  and  Down  123 

force  additional  to  that  necessary  to  maintain  the  velocity 
attained.  Apparently,  therefore,  any  self -starting  machine 
must  have  not  only  the  extra  weight  of  framework  and 
wheels  but  also  extra  motor  power. 

Upon  closer  examination  of  the  matter,  we  may  find  a 
particularly  fortunate  condition  of  things  in  the  aeroplane. 
Both  sustaining  power  and  resistance  vary  with  the  incli- 
nation of  the  planes,  as  indicated  by  the  chart  on  page  24. 
It  is  entirely  possible  to  start  with  no  such  inclination,  so 
that  the  direct  wind  resistance  is  eliminated.  The  motor 
must  then  overcome  only  air  friction,  in  addition  to  pro- 
viding an  accelerating  force.  The  machine  runs  along  the 
ground,  its  velocity  rapidly  increasing.  As  soon  as  the 
necessary  speed  (or  one  somewhat  greater)  is  attained, 
the  planes  are  tilted  and  the  aeroplane  lises  from  the 
ground. 

The  velocity  necessary  to  just  sustain  the  load  at  a 
given  angle  of  inclination  is  called  the  critical  or  soaring 
velocity.  For  a  given  machine,  there  is  an  angle  of  incli- 
nation (about  half  a  right  angle)  at  which  the  minimum 
speed  is  necessary.  This  speed  is  called  the  "least  soaring 
velocity."  If  the  velocity  is  now  increased,  the  angle  of 
inclination  may  be  reduced  and  the  planes  will  soar  through 
the  air  almost  edgewise,  apparently  with  diminished  resist- 
ance and  power  consumption.  This  decrease  in  power 
as  the  speed  increases  is  called  Langley's  Paradox,  from 
its  discoverer,  who,  however,  pointed  out  that  the  rule 
does  not  hold  in  practice  when  frictional  resistances  are 


124 


Flying  Machines  Today 


Getting  Up  and  Down 


125 


included.  We  cannot  expect  to  actually  save  power  by 
moving  more  rapidly  than  at  present;  but  we  should  have 
to  provide  much  more  power  if  we  tried  to  move  much 
more  slowly. 


ft:: 


A  BIPLANE 
(From  Aircraft) 


126 


Flying  Machines  Today 


Economical  and  practicable  starting  of  an  aeroplane  thus 
requires  a  free  launching  space,  along  which  the  machine 
may  accelerate  with  nearly  flat  planes:  a  downward  slope 
would  be  an  aid.  When  the  planes  are  tilted  for  ascent, 
after  attaining  full  speed,  quick  control  is  necessary  to 
avoid  the  possibility  of  a  back-somersault.  A  fairly  wide 


(Photo  by  American  Press  Association) 

ELY  AT  Los  ANGELES 

launching  platform  of  200  feet  length  would  ordinarily 
suffice.  The  flight  made  by  Ely  in  January  of  this  year, 
from  San  Francisco  to  the  deck  of  the  cruiser  Pennsylvania 
and  back,  demonstrated  the  possibility  of  starting  from  a 
limited  area.  The  wooden  platform  built  over  the  after 


Getting  Up  and  Down  127 

deck  of  the  warship  was  130  feet  long,  and  sloped.  On 
the  return  trip,  the  aeroplane  ran  down  this  slope,  dropped 
somewhat,  and  then  ascended  successfully. 

If  the  effort  is  made  to  ascend  at  low  velocities,  then  the 
motor  power  must  be  sufficient  to  propel  the  machine  at 
an  extreme  angle  of  inclination  —  perhaps  the  third  of  a 
right  angle,  approximating  to  the  angle  of  least  velocity 
for  a  given  load.  According  to  Chatley,  this  method  of 
starting  by  Farman  at  Issy-les-Molineaux  involved  the 
use  of  a  motor  of  fifty  horse-power:  while  Roe's  machine 
at  Brooklands  rose,  it  is  said,  with  only  a  six  horse-power 
motor. 

DESCENDING 

What  happens  when  the  motor  stops?  The  velocity 
of  the  machine  gradually  decreases:  the  resistance  to 
forward  movement  stops  its  forward  movement  and  the 


Horizontal 


excess  of  weight  over  upward  pressure  due  to  velocity 
causes  it  to  descend.  It  behaves  like  a  projectile,  but 
the  details  of  behavior  are  seriously  complicated  by  the 
variation  in  head  resistance  and  sustaining  force  due  to 


Getting  Up  and  Down  129 

changes  in  the  angle  of  the  planes.  The  "angle  of  inclina- 
tion" is  now  not  the  angle  made  by  the  planes  with  the 
horizontal,  but  the  angle  which  they  make  with  the  path 
of  flight.  Theory  indicates  that  this  should  be  about  two- 
thirds  the  angle  which  the  path  itself  makes  with  the 
horizontal:  that  is,  the  planes  themselves  are  inclined 
downward  toward  the  front.  The  forces  which  determine 
the  descent  are  fixed  by  the  velocity  and  the  angle  between 
the  planes  and  the  path  of  flight.  Manipulation  of  the 
rudders  and  main  planes  or  even  the  motor  may  be  prac- 
tised to  ensure  lancing  to  best  advantage;  but  in  spite  of 
these  (or  perhaps  on  account  of  these.)  scarcely  any  part 
of  aviation  offers  more  dangers,  demands  more  genius  on 
the  part  of  the  operator,  and  has  been  less  satisfactorily 
analyzed  than  the  question  of  " getting  down."  It  is 
easy  to  stay  up  and  not  very  hard  to  "get  up,"  weather 
conditions  being  favorable;  but  it  is  an  "all-sufficient 
job"  to  come  down.  Under  the  new  rules  of  the  Inter- 
national Aeronautic  Federation,  a  test  flight  for  a  pilot's 
license  must  terminate  with  a  descent  (motor  stopped) 
in  which  the  aviator  is  to  land  within  fifty  yards  of  the 
observers  and  come  to  a  full  stop  inside  of  fifty  yards  there- 
from. The  elevation  at  the  beginning  of  descent  must 

be  at  least  150  feet. 

GLIDERS 

If  the  motor  and  its  appurtenances,  and  some  of  the 
purely  auxiliary  planes,  be  omitted,  we  have  a  glider.  The 
glider  is  not  a  toy;  some  of  the  most  important  problems 


130 


Flying  Machines  Today 


of  balancing  may  perhaps  be  some  day  solved  by  its  aid. 
Any  boy  may  build  one  and  fly  therewith,  although  a 
large  kite  promises  greater  interest.  The  cost  is  trifling, 
if  the  framework  is  of  bamboo  and  the  surfaces  are  cotton. 
Areas  of  glider  surfaces  frequently  exceed  100  square  feet. 
This  amount  of  surface  is  about  right  for  a  person  of  mod- 


THE  WITTEMAN  GLIDER 

erate  weight  if  the  machine  itself  does  not  weigh  over 
fifty  pounds.  By  running  down  a  slope,  sufficient  velocity 
may  be  attained  to  cause  ascent;  or  in  a  favorable  wind 
(up  the  slope)  a  considerable  backward  flight  may  be 
experienced.  Excessive  heights  have  led  to  fatal  accidents 
in  gliding  experiments. 


Getting  Up  and  Down  131 

MODELS 

The  building  of  flying  models  has  become  of  commercial 
importance.  It  is  not  difficult  to  attain  a  high  ratio  of 
surface  to  weight,  but  it  is  almost  impossible  to  get  motor 
power  in  the  small  units  necessary  without  exceeding  the 
permissible  limit  of  motor  weight.  No  gasoline  engine 
or  electric  motor  can  be  made  sufficiently  light  for  a  toy 
model.  Clockwork  springs,  if  especially  designed,  may 
give  the  necessary  power  for  short  flights,  but  no  better 
form  of  power  is  known  just  now  than  the  twisted  rubber 
band.  For  the  small  boy,  a  biplane  with  sails  about 
eighteen  inches  by  four  feet,  eighteen  inches  apart, 
anchored  under  his  shoulders  by  six-foot  cords  while  he 
rides  his  bicycle,  will  give  no  small  amount  of  experience 
in  balancing  and  will  support  enough  of  a  load  to  make 
the  experiment  interesting. 

SOME  DETAILS:  BALANCING 

It  is  easily  possible  to  compute  the  areas,  angles,  and 
positions  of  auxiliary  planes  to  give  desired  controlling  or 
stabilizing  effects;  but  the  computation  involves  the  use 
of  accurate  data  as  to  positions  of  the  various  weights,  and 
on  the  whole  it  is  simpler  to  correct  preliminary  calcula- 
tions by  actually  supporting  the  machine  at  suitable 
points  and  observing  its  balance.  Stability  is  especially 
uncertain  at  very  small  angles  of  inclination,  and  such  angles 
are  to  be  avoided  whether  in  ordinary  operation  or  in 


132  Flying  Machines  Today 

descent.  The  necessity  for  rotating  main  planes  in  order 
to  produce  ascent  is  disadvantageous  on  this  ground;  but 
the  proposed  use  of  sliding  or  jockey  weights  for  supple- 


FRENCH  MONOPLANE 
(From  Aircraft) 

mentary  balancing  appears  to  be  open  to  objections  no 
less  serious.  Steering  may  be  perceptibly  assisted,  in  as 
delicately  a  balanced  device  as  the  aeroplane,  by  the 


Getting  Up  and  Down  133 

inclination  of  the  body  of  the  operator,  just  as  in  a  bicycle. 
The  direction  of  the  wind  in  relation  to  the  required  course 
may  seriously  influence  the  steering  power.  Suppose  the 
course  to  be  northeast,  the  wind  east,  the  independent 
speed  of  the  machine  and  that  of  the  wind  being  the  same. 
The  car  will  head  due  north.  By  bringing  the  rudder  in 
position  (a),  the  course  may  be  changed  to  north,  or 
nearly  so,  the  wind  exerting  a  powerful  pressure  on  the 

Wind  E. 


b    Rudder  position 

to  make  course  E-N.E. 
(ineffective) 


-Rudder  position 
to  make  course 
approximately  N  -  N.  E . 


rudder;  but  if  a  more  easterly  or  east-northeast  course 
be  desired,  and  the  rudder  be  thrown  into  the  usual  posi- 
tion therefor  (b),  it  will  exert  no  influence  whatever, 
because  it  is  moving  before  the  wind  and  precisely  at  the 
speed  of  the  wind. 

It  might  be  thought  that,  following  analogies  of  marine 
engineering,  the  center  of  gravity  of  an  aeroplane  should 
be  kept  low.  The  effect  of  any  unbalanced  pressure  or 
force  against  the  widely  extended  sails  of  the  machine  is 
to  rotate  the  whole  apparatus  about  its  center  of  gravity. 


Getting  Up  and  Down  135 

The  further  the  force  from  the  center  of  gravity,  the  more 
powerful  is  the  force  in  producing  rotation.  The  defect 
in  most  aeroplanes  (especially  biplanes)  is  that  the  center 
of  gravity  is  too  low.  If  it  could  be  made  to  coincide  with 
the  center  of  disturbing  pressure,  there  would  be  no  un- 
balancing effect  from  the  latter.  It  is  claimed  that  the 
steadiest  machines  are  those  having  a  high  center  of  grav- 
ity; and  the  claim,  from  these  considerations,  appears 
reasonable. 

WEIGHTS 

It  has  been  found  not  difficult  to  keep  down  the  weight 
of  framework  and  supporting  surfaces  to  about  a  pound 
per  square  foot.  The  most  common  ratio  of  surface  to 


THE  TELLIER  TWO-SEAT  SIX-CYLINDER  MONOPLANE  AT  THE 

PARIS  SHOW 

One  of  this  type  has  been  sold  to  the  Russian  Government 
(From  Aircraft] 

total  weight  is  about  one  to  two:  so  that  the  machinery 
and  operator  will  require  one  square  foot  of  surface  for 
each  pound  of  their  weight.  On  this  basis,  the  smallest 
possible  man-carrying  aeroplane  would  have  a  surface 


136  Flying  Machines  Today 

scarcely  below  250  square  feet.  Most  biplanes  have  twice 
this  surface:  a  thousand  square  feet  seems  to  be  the 
limit  without  structural  weakness.  Some  recent  French 
machines,  designed  for  high  speeds,  show  a  greatly  in- 
creased ratio  of  weight  to  surface.  The  Hanriot,  a  mono- 
plane with  wings  upwardly  inclined  toward  the  outer 
edge,  carries  over  800  pounds  on  less  than  300  square  feet. 
The  Farman  monoplane  of  only  180  square  feet  sustains 
over  600  pounds.  The  same  aviator's  racing  biplane  is 
stated  to  support  nearly  900  pounds  on  less  than  400 
square  feet. 

Motor  weights  can  be  brought  down  to  about  two  pounds 
per  horse-power,  but  such  extreme  lightness  is  not  always 
needed  and  may  lead  to  unreliability  of  operation.  The 
effect  of  an  accumulation  of  ice,  sleet,  snow,  rain,  or  dew 
might  be  serious  in  connection  with  flights  in  high  alti- 
tudes or  during  bad  weather.  After  one  of  his  last  year's 
flights  at  Etampes  Mr.  Farman  is  said  to  have  descended 
with  an  extra  load  of  nearly  200  pounds  on  this  account. 
With  ample  motor  power,  great  flexibility  in  weight  sus- 
tention is  made  possible  by  varying  the  inclination  of  the 
planes.  In  January  of  this  year,  Sommer  at  Douzy  car- 
ried six  passengers  in  a  large  biplane  on  a  cross-country 
flight:  and  within  the  week  afterward  a  monoplane  oper- 
ated by  Le  Martin  flew  for  five  minutes  with  the  aeronaut 
and  seven  passengers,  at  Pau.  The  total  weight  lifted 
was  about  half  a  ton,  and  some  of  the  passengers  must 
have  been  rather  light.  The  two-passenger  Fort  Myer 


Getting  Up  and  Down  137 

biplane  of  the  Wright  brothers  is  understood  to  have  car- 
ried about  this  total  weight.     These  records  have,  how- 


-jLUJ-LU. 

fithiti 

4.U.1LUL 


A  MONOPLANE 
(From  Aircraft) 


ever,  been  surpassed  since  they  were  noted.     Breguet,  at 
Douai,  in  a  deeply-arched  biplane  of  new  design,  carried 


138  Flying  Machines  Today 

eleven  passengers,  the  total  load  being  2602  pounds,  and 
that  of  aeronaut  and  passengers  alone  1390  pounds.  The 
flight  was  a  short  one,  at  low  altitude;  but  the  same  aviator 
last  year  made  a  long  flight  with  five  passengers,  and  carried 
a  load  of  1262  pounds  at  62  miles  per  hour.  And  as  if 
in  reply  to  this  feat,  Sommer  carried  a  live  load, of  1436 
pounds  (13  passengers)  for  nearly  a  mile,  a  day  or  two 
later,  at  Mouzon  One  feels  less  certain  than  formerly, 
now,  in  the  snap  judgment  that  the  heavier-than-air 
machine  will  never  develop  the  capacity  for  heavy  loads. 

MISCELLANEOUS 

French  aviators  are  fond  of  employing  a  carefully  de- 
signed car  for  the  operator  and  control  mechanism.  The 
Wright  designs  practically  ignore  the  car:  the  aviator  sits 
on  the  forward  edge  of  the  lower  plane  with  his  legs  hang- 
ing  over. 

It  has  been  found  that  auxiliary  planes  must  not  be 
too  close  to  the  main  wings:  a  gap  of  a  distance  about 
50%  greater  than  the  width  of  the  widest  adjacent  plane 
must  be  maintained  if  interference  with  the  supporting  air 
currents  is  to  be  avoided.  Main  planes  are  now  always 
arched;  auxiliary  planes,  not  as  universally.  The  concave 
under  surface  of  supporting  wings  has  its  analogy  in  the 
wing  of  the  bird  and  had  long  years  since  been  applied  in 
the  parachute. 

The  car  (if  used)  and  all  parts  of  the  framework  should 
be  of  "wind  splitter"  construction,  if  useless  resistance  is 


Getting  Up  and  Down  139 

to  be  avoided.     The  ribs  and  braces  of  the  frame  are  of 
course  stronger,  weight  for  weight,  in  this  shape,  since  a 


Sectional  Views  of  Ribs 


narrow  deep  beam  is  always  relatively  stronger  than  one 
of  square  or  round  section.  Excessive  frictional  resist- 
ance is  to  be  avoided  by  using  a  smoothly  finished  fabric 
for  the  wings,  and  the  method  of  attaching  this  fabric 


^Steering  Rudder 

.Stabilising  Planes 


A  Double  Biplane 


New  Position 
for  Ailerons 


to  the  frame  should  be  one  that  keeps  it  as  flat  as  pos- 
sible at  all  joints. 

The  sketches  give  the  novel  details  of  some  machines 
recently  exhibited  at  the  Grand  Central  Palace  in  New 


140  Flying  Machines  Today 

York.     The  stabilizing  planes  were  invariably  found  in 
the  rear,  in  all  machines  exhibited. 

THE  THINGS  TO  LOOK  AFTER 

The  operator  of  an  aeroplane  has  to  do  the  work  of  at 
least  two  men.  No  vessel  in  water  would  be  allowed  to 
attain  such  speeds  as  are  common  with  air  craft,  unless 
provided  with  both  pilot  and  engineer.  The  aviator  is 
his  own  pilot  and  his  own  engineer.  He  must  both  man- 
age his  propelling  machinery  and  steer.  Separate  control 
for  vertical  rudders,  elevating  rudders  and  ailerons,  for 
starting  the  engine;  the  adjustment  of  the  carbureter,  the 
spark,  and  the  throttle  to  get  the  best  results  from  the 
motor;  attention  to  lubrication  and  constant  watchfulness 
of  the  water- circulating  system:  these  are  a  few  of  the  things 
for  him  to  consider;  to  say  nothing  of  the  laying  of  his 
course  and  the  necessary  anticipation  of  wind  and  alti- 
tude conditions. 

These  things  demand  great  resourcefulness,  but  —  for 
their  best  control  —  involve  also  no  small  amount  of  scien- 
tific knowledge.  For  example,  certain  adjustments  at 
the  motor  may  considerably  increase  its  power,  a  possibly 
necessary  increase  under  critical  conditions:  but  if  such 
adjustments  also  decrease  the  motor  efficiency  there  must 
be  a  nice  analysis  of  the  two  effects  so  that  extra  power 
may  not  be  gained  at  too  great  a  cost  in  radius  of  action. 

The  whole  matter  of  flight  involves  both  sportsman's 
and  engineer's  problems.  Wind  gusts  produce  the  same 


142  Flying  Machines  Today 

effects  as  " turning  corners";  or  worse  —  rapidly  changing 
the  whole  balance  of  the  machines  and  requiring  im- 
mediate action  at  two  or  three  points  of  control.  Both 
ascent  and  descent  are  influenced  by  complicated  laws  and 
are  scarcely  rendered  safe  —  under  present  conditions  - 
by  the  most  ample  experience.  A  lateral  air  current 
bewilders  the  steering  and  also  demands  special  prompt- 
ness and  skill.  To  avoid  disturbing  surface  winds,  even 
over  open  country,  a  minimum  flying  height  of  300  feet 
is  considered  necessary.  This  height,  furthermore,  gives 
more  choice  in  the  matter  of  landing  ground  than  a  lower 
elevation. 

When  complete  and  automatic  balance  shall  have  been 
attained  —  as  it  must  be  attained — we  may  expect  to 
see  small  amateur  aeroplanes  flying  along  country  roads 
at  low  elevations  —  perhaps  with  a  guiding  wheel  actually 
in  contact  with  the  ground.  They  will  cost  far  less  than 
even  a  small  automobile,  and  the  expense  for  upkeep  will 
be  infinitely  less.  The  grasshopper  will  have  become  a 
water-spider. 


SOME    AEROPLANES  —  SOME    ACCOMPLISH- 
MENTS 

THE  Wright  biplane  has  already  been  shown  (see  pages 
31,  37,'  121,  122).     It  was  distinguished  by  the  absence 


ORVILLE  WRIGHT  AT  FORT  MYER,  VA.,  1908 

of  a  wheel  frame  or  car  and  by  the  wing- warping  method  of 
stabilizing.  Later  Wright  machines  have  the  spring  frame 
and  wheels  for  self-starting.  The  best  known  aeroplane 
of  this  design  was  built  to  meet  specifications  of  the  United 

143 


Some  Aeroplanes  —  Some  Accomplishments         145 


States  Signal  Corps  issued  in  1907.  It  was  tried  out 
during  1908  at  Fort  Myer,  Va.,  while  one  of  the  Wright 
brothers  was  breaking  all  records  in  Europe:  making 


11  II          11  i 


WRIGHT  MOTOR.     Dimensions  in  millimeters 
(From  Petit's  How  to  Build  an  Aeroplane) 

over  a  hundred  flights  in  all,  first  carrying  a  passenger 
and  attaining  the  then  highest  altitude  (360  feet)  and 
greatest  distance  of  flight  (seventy-seven  miles). 

The   ownership   of    the   Wrights   in   the    wing-warping 


146  Flying  Machines  Today 

method  of  control  is  still  the  subject  of  litigation.  The 
French  infringers,  it  is  stated,  concede  priority  of  appli- 
cation to  the  Wright  firm,  but  maintain  that  such  pub- 
licity was  given  the  device  that  it  was  in  general  use 
before  it  was  patented. 

The  Fort  Myer  machine  had  sails  of  forty  feet  spread, 
six  and  one-half  feet  deep,  with  front  elevating  planes 
three  by  sixteen  feet.  It  made  about  forty  miles  per  hour 
with  two  passengers.  The  apparatus  was  specified  to 
carry  a  passenger  weight  of  350  pounds,  with  fuel  for  a 
125-mile  flight.  The  main  planes  were  six  feet  apart. 
The  steering  rudder  (double)  was  of  planes  one  foot  deep 
and  nearly  six  feet  high.  The  four-cylinder-four-cycle, 
water-cooled  motor  developed  twenty-five  horse-power  at 
1400  revolutions.  The  two  propellers,  eight  and  one-half 
feet  in  diameter,  made  400  revolutions. 

The  flight  by  Mr.  Wilbur  Wright  from  the  Statue  of 
Liberty  to  the  tomb  of  General  Grant,  in  New  York,  1909, 
and  the  exploits  of  his  brother  in  the  same  year,  when  a  new 
altitude  record  of  1600  feet  was  made  and  H.R.H.  the 
Crown  Prince  of  Germany  was  taken  up  as  a  passenger, 
are  only  specimens  of  the  later  work  done  by  these  pioneers 
in  aerial  navigation. 

Like  the  Wrights,  the  Voisin  firm  from  the  beginning 
adhered  firmly  to  the  biplane  type  of  machine.  The 
sketch  gives  dimensions  of  one  of  the  early  cellular  forms 
built  for  H.  Farman  (see  illustration,  page  147).  The 
metal  screw  makes  about  a  thousand  revolutions.  The 


Some  Aeroplanes  —  Some  Accomplishments        147 


wings  are  of  India  rubber  sheeting  on  an  ash  frame,  the 
whole  frame  and  car  body  being  of  wood,  the  latter  cov- 
ered with  canvas  and  thirty  inches  wide  by  ten  feet  long. 
The  engine  weighed  175  pounds.  The  whole  weight  of 
this  machine  was  nearly  1200  pounds;  that  built  later  for 
Delagrange  was  brought  under  a  thousand  pounds.  The 
ratio  of  weight  to  main  surface  in  the  Farm  an  aeroplane 
was  about  2!  to  i. 

A  modified  cellular  biplane  also  built  for  Farman  had  a 
main  wing  area  of  560  square  feet,  the  planes  being  sev- 


jSil^aaeg'  /Steering  Rudder 


Usual  Flying  Angle 
6  to  8  deg. 


Elevating  Rudder 


K 

I  Line  of  center  of  weight 
'  in  ordinary  operation 

VOISIN-FARMAN    BlPLANE 

enty-nine  inches  wide  and  only  fifty-nine  inches  apart. 
The  tail  was  an  open  box,  seventy-nine  inches  wide  and  of 
about  ten  feet  spread.  The  cellular  partitions  in  this  tail 
were  pivoted  along  the  vertical  front  edges  so  as  to  serve 
as  steering  rudders.  The  elevating  rudder  was  in  front. 
The  total  weight  was  about  the  same  as  that  of  the  first 
machine  and  the  usual  speed  twenty-eight  miles  per  hour. 
Henry  Farman  has  been  flying  publicly  since  1907.  He 


148  Flying  Machines  Today 

made  the  first  circular  flight  of  one  kilometer,  and  attained 
a  speed  of  about  a  mile  a  minute,  in  the  year  following. 


THE  CHAMPAGNE  GRAND  PRIZE  WON  BY  HENRY  FARMAN 
80  Kilometers  in  3  hours 

In  1909  he  accomplished  a  trip  of  nearly  150  miles,  remain- 
ing four  hours  in  the  air.  Farman  was  probably  the  first 
man  to  ascend  with  two  passengers. 


150  Flying  Machines  Today 

The  June  Bug,  one  of  the  first  Curtiss  machines,  is 
shown  below.  This  was  one  of  the  lightest  of  biplanes, 
having  a  wing  spread  of  forty-two  feet  and  an  area  of 
370  square  feet.  The  wings  were  transversely  arched, 
being  furthest  apart  at  the  center:  an  arrangement  which 
has  not  been  continued.  It  had  a  box  tail,  with  a  steer- 
ing rudder  of  about  six  square  feet  area,  above  the  tail. 
The  horizontal  rudder,  in  front,  had  a  surface  of  twenty 


THE  "JUNE  BUG" 

square  feet.  Four  triangular  ailerons  were  used  for  stabil- 
ity. The  machine  had  a  landing  frame  and  wheels,  made 
about  forty  miles  per  hour,  and  weighed,  in  operation, 
650  pounds. 

Mr.  Curtiss  first  attained  prominence  in  aviation  circles 
by  winning  the  Scientific  American  cup  by  his  flight  at 
the  speed  of  fifty-seven  miles  per  hour,  in  1908.  In  the 
following  year  he  exhibited  intricate  curved  flights  at 
Mineola,  and  circled  Governor's  Island  in  New  York 


Some  Aeroplanes  —  Some  Accomplishments        151 

harbor.  In  1910  he  made  his  famous  flight  from  Albany 
to  New  York,  stopping  en  route,  as  prearranged.  At 
Atlantic  City  he  flew  fifty  miles  over  salt  water.  A  flight 
of  seventy  miles  over  Lake  Erie  was  accomplished  in  Sep- 
tember of  the  same  year,  the  return  trip  being  made  the 
following  day.  On  January  26,  1911,  Curtiss  repeatedly 


(Photo  by  Levick,  N.Y.) 

CURTISS  BIPLANE 

ascended  and  descended,  with  the  aid  of  hydroplanes,  in 
San  Diego  bay,  California:  perhaps  one  of  the  most  im- 
portant of  recent  achievements.  It  is  understood  that 
Mr.  Curtiss  is  now  attempting  to  duplicate  some  of  these 
performances  under  the  high-altitude  conditions  of  Great 
Salt  Lake.  According  to  press  reports,  he  has  been  invited 


152  Flying  Machines  Today 

to  give  a  similar  demonstration  before  the  German  naval 
authorities  at  Kiel. 

The  aeroscaphe  of  Ravard  was  a  machine  designed  to 
move  either  on  water  or  in  air.     It  was  an  aeroplane  with 


CURTISS'  HYDRO-AEROPLANE  AT  SAN  DIEGO  GETTING  UNDER  WAY 
(From  the  Columbian  Magazine) 

pontoons  or  floaters.  The  supporting  surface  aggregated 
400  square  feet,  and  the  gross  weight  was  about  noo 
pounds.  A  fifty  horse-power  Gnome  seven-cylinder  motor 
at  1 200  revolutions  drove  two  propellers  of  eight  and 
ten  and  one-half  feet  diameter  respectively:  the  propel- 


Some  Aeroplanes  —  Some  Accomplishments        153 

lers  being  mounted  one  behind  the  other  on   the  same 
shaft. 

Ely's  great  shore-to-warship  flight  was  made  without 
the  aid  of  the  pontoons  which  he  carried.  Ropes  were 
stretched  across  the  landing  platform,  running  over  sheaves 
and  made  fast  to  heavy  sand  bags.  As  a  further  precau- 


FLYING  OVER  THE  WATER  AT  FIFTY  MILES  PER  HOUR 

Curtiss  at  San  Diego  Bay 
(From  the  Columbian  Magazine) 

tion,  a  canvas  barrier  was  stretched  across  the  forward 
end  of  the  platform.  The  descent  brought  the  machine 
to  the  platform  at  a  distance  of  forty  feet  from  the  upper 
end:  grappling  hooks  hanging  from  the  framework  of  the 
aeroplane  then  caught  the  weighted  ropes,  and  the  speed 
was  checked  (within  about  sixty  feet)  so  gradually  that 
"not  a  wire  or  bolt  of  the  biplane  was  injured." 


156 


Flying  Machines  Today 


Some  Aeroplanes  —  Some  Accomplishments         157 


158  Flying  Machines  Today 

Recent  combinations  of  aeroplane  and  automobile, 
and  aeroplane  with  motor  boat,  have  been  exhibited. 
One  of  the  latter  devices  is  like  any  monoplane,  except 
that  the  lower  part  is  a  water-tight  aluminum  boat  body 
carrying  three  passengers.  It  is  expected  to  start  of  itself 
from  the  water  and  to  fly  at  a  low  height  like  a  flying 
fish  at  a  speed  of  about  seventy-five  miles  per  hour. 
Should  anything  go  wrong,  it  is  capable  of  floating  on 
the  water.  ._;• 

In  the  San  Diego  Curtiss  flights,  the  machine  skimmed 
along  the  surface  of  the  bay,  then  rose  to  a  height  of  a 
hundred  feet,  moved  about  two  miles  through  the  air  in  a 
circular  course,  and  finally  alighted  close  to  its  starting- 
point  in  the  water.  Turns  were  made  in  water  as  well  as 
in  air,  a  speed  of  forty  miles  per  hour  being  attained  while 
"skimming."  The  "hydroplanes''  used  are  rigid  flat 
surfaces  which  utilize  the  pressure  of  the  water  for  sus- 
tention, just  as  the  main  wings  utilize  air  pressure.  On 
account  of  the  great  density  of  water,  no  great  amount  of 
surface  is  required:  but  it  must  be  so  distributed  as  to 
balance  the  machine.  The  use  of  pontoons  makes  it  pos- 
sible to  rest  upon  the  water  and  to  start  from  rest.  A  trip 
like  Ely's  could  be  made  without  a  landing  platform,  with 
this  type  of  machine;  the  aeroplane  could  either  remain 
alongside  the  war  vessel  or  be  hoisted  aboard  until  ready 
to  venture  away  again. 

There  are  various  other  biplanes  attracting  public  atten- 
tion in  this  country.  In  France  the  tendency  is  all  toward 


Some  Aeroplanes  —  Some  Accomplishments        159 

the  monoplane  form,  and  many  of  the  " records"  have,  dur- 
ing the  past  couple  of  years,  passed  from  the  former  to 


SANTOS-DUMONT'S      DEMOISELLE 


the  latter  type  of  machine.     The  monoplane  is  simpler 
and  usually  cheaper.     The  biplane  may  be  designed  for 


i6o 


Flying  Machines  Today 


greater  economy  in  weight  and  power.  Farman  has 
lately  experimented  with  the  monoplane  type  of  machine: 
the  large  number  of  French  designs  in  this  class  discourages 
any  attempt  at  complete  description. 

The  smallest  of  aeroplanes  is  the  Santos-Dumont  Dem- 
oiselle. The  original  machine  is  said  to  have  supported 
260  pounds  on  100  square  feet  of  area,  making  a  speed  of 
sixty  miles  per  hour.  Its  proprietor  was  the  first  aviator 


BLERIOT  MONOPLANE 

in  Europe  of  the  heavier-than-air  class.  After  having 
done  pioneer  work  with  dirigible  balloons,  he  won  the 
Deutsch  prize  for  a  hundred  meter  aeroplane  flight  (the 
first  outside  of  the  United  States)  in  1906;  the  speed  being 
twenty-three  miles  per  hour.  His  first  flight,  of  400  feet, 
in  a  monoplane  was  made  in  1907. 

The  master  of  the  monoplane  has  been  Louis  Bleriot. 
Starting  in  1907  with  short  flights  in  a  Langley  type  of 


Some  Aeroplanes  —  Some  Accomplishments        161 

machine,  he  made  his   celebrated  cross-country  run,  and 
the  first  circling  flights  ever  achieved  in  a  monoplane,  the 


LATHAM'S  FALL  INTO  THE  CHANNEL 

following  year.     On  July  25,  1909,  he  crossed  the  British 
Channel,  thirty-two  miles,  in  thirty-seven  minutes. 
The  Channel  crossing  has  become  a  favorite  feat.     Mr. 


1 62  Flying  Machines  Today 

Latham,  only  two  days  after  Bleriot,  all  but  completed 
it  in  his  Antoinette  monoplane.  De  Lesseps,  in  a 
Bleriot  machine,  was  more  fortunate.  Sopwith,  last 
year,  won  the  de  Forest  prize  of  $20,000  by  a  flight  of 
174  miles  from  England  into  Belgium.  The  ill-fated 
Rolls  made  the  round  trip  between  England  and  France. 
Grace,  contesting  for  the  same  prize,  reached  Belgium, 
was  driven  back  to  Calais,  started  on  the  return  voyage, 
and  vanished  —  all  save  some  few  doubtful  relics  lately 
found.  Moisant  reached  London  from  Paris  —  the  first 
trip  on  record  between  these  cities  without  change  of 
conveyance:  and  one  which  has  just  been  duplicated  by 
Pierre  Prier,  who,  on  April  12,  made  the  London  to  Paris 
journey,  290  miles,  in  236  minutes,  without  a  stop.  This 
does  not,  however,  make  the  record  for  a  continuous  flight : 
which  was  attained  by  Tabuteaw,  who  at  Buc,  on  Dec.  30, 
1910,  flew  around  the  aerodrome  for  465  minutes  at  the 
speed  of  48  \  miles  per  hour. 

Other  famous  crossings  include  those  of  the  Irish  Sea, 
52  miles,  by  Loraine;  Long  Island  Sound,  25  miles,  by 
Harmon;  and  Lake  Geneva,  40  miles,  by  Defaux. 

It  was  just  about  a  century  ago  that  Cayley  first  de- 
scribed a  soaring  machine,  heavier  than  air,  of  a  form  re- 
markably similar  to  that  of  the  modern  aeroplane.  Aside 
from  Henson's  unsuccessful  attempt  to  build  such  a  ma- 
chine, in  1842,  and  Wenham's  first  gliding  experiments 
with  a  triplane  in  1857,  soaring  flight  made  no  real  progress 
until  Langley's  experiments.  That  investigator,  with 


Some  Aeroplanes  —  Some  Accomplishments        163 


.  -Jl 


164  Flying  Machines  Today 

Maxim  and  others,  ascertained  those  laws  of  aerial  sus- 
tention the  application  of  which  led  to  success  in  1903. 

The  eight  years  since  have  held  the  crowded  hours  of 
aviation.  Before  this  book  is  printed,  it  may  be  rendered 
obsolete  by  new  developments.  The  exploits  of  Paulhan, 
of  R.  E.  Pelterie  since  1907,  Bell's  work  with  his  tetrahe- 
dral  kites  —  all  have  been  either  stimulating  or  directly 
fruitful.  Delagrange  began  to  break  speed  records  in  1908. 


THE  MAXIM  AEROPLANE 

A  year  later  he  attained  a  speed  of  fifty  miles.  The  first 
woman  to  enjoy  an  aeroplane  voyage  was  Mme.  Dela- 
grange, in  Turin,  in  1908. 

The  first  flight  in  England  by  an  English-built  machine 
was  made  in  January,  1909.  That  year,  Count  de  Lam- 
bert flew  over  Paris,  and  in  1910  Grahame- White  ciicled 
his  machine  over  the  city  of  Boston.  The  year  1910  sur- 


1 66  Flying  Machines  Today 

passed  all  its  predecessors  in  increasing  the  range  and 
control  of  aeroplanes;  over  1500  ascents  were  made  by 
Wright  machines  alone;  but  1911  promises  to  show  even 
greater  results.  Three  men  made  cross-country  flights 
from  Belmont  Park  to  the  Statue  of  Liberty  and  back, 


ROB  ART  MONOPLANE. 

in  New  York;*  at  least  five  men  attained  altitudes  exceed- 
ing 9,000  feet.  Hamilton  made  the  run  from  New  York 
to  Philadelphia  and  return,  in  June.  The  unfortunate 
Chavez  all  but  abolished  the  fames  of  Hannibal  and  Napo- 

*  The  contestants  for  the  Ryan  prize  of  $10,000  were  Moisant,  Count 
de  Lesseps,  and  Grahame -White.  Owing  to  bad  weather,  there  was  no 
general  participation  in  the  preliminary  qualifying  events,  and  some  ques- 
tion exists  as  to  whether  such  qualification  was  not  tacitly  waived;  par- 
ticularly in  view  of  the  fact  that  the  prize  was  awarded  to  the  technically 
unqualified  competitor,  Mr.  Moisant,  who  made  the  fastest  time.  This 
award  was  challenged  by  Mr.  Grahame- White,  and  upon  review  by  the 
International  Aeronautic  Federation  the  prize  was  given  to  de  Lesseps,  the 
slowest  of  the  contestants,  Grahame-White  being  disqualified  for  having 
fouled  a  pylon  at  the  start.  This  gentleman  has  again  appealed  the  case, 
and  a  final  decision  cannot  be  expected  before  the  meeting  of  the  Federa- 
tion in  October,  1911. 


Some  Aeroplanes  —  Some  Accomplishments        167 

Icon  by  crossing  the  icy  barrier  of  the  Alps,  from  Switzer- 
land to  Italy  —  in  forty  minutes ! 

Tabuteau,  almost  on  New  Year's  eve,  broke  all  distance 
records  by  a  flight  of  363  miles  in  less  than  eight  hours; 
while  Barrier  at  Memphis  probably  reached  a  speed  of 
eighty-eight  miles  per  hour  (timing  unofficial).  With  the 
new  year  came  reports  of  inconceivable  speeds  by  a  ma- 
chine skidding  along  the  ice  of  Lake  Erie;  the  successful 


VINA  MONOPLANE 

receipt  by  Willard  and  McCurdy  of  wireless  messages 
from  the  earth  to  their  aeroplanes;  and  the  proposal  by 
the  United  States  Signal  Corps  for  the  use  of  flying 
machines  for  carrying  Alaskan  mails. 

McCurdy  all  but  succeeded  in  his  attempt  to  fly  from 
Key  West  to  Havana,  surpassing  previous  records  by 
remaining  aloft  above  salt  water  while  traveling  eighty 
miles.  Lieutenant  Bague,  in  March,  started  from  Antibes, 
near  Nice,  for  Corsica.  After  a  1 24-mile  flight,  breaking  all 
records  for  sea  journeys  by  air,  he  reached  the  islet  of  Gor- 


1 68  Flying  Machines  Today 

gona,  near  Leghorn,  Italy,  landing  on  bad  ground  and  badly 
damaging  his  machine.  The  time  of  flight  was  5^  hours. 
Bellinger  completed  the  5oo-mile  " accommodation  train" 
flight  from  Vincennes  to  Pau;  Vedrine,  on  April  12,  by 
making  the  same  journey  in  415  minutes  of  actual  flying 
time,  won  the  Beam  prize  of  $4000;  Say  attained  a  speed 
of  74  miles  per  hour  in  circular  flights  at  Issy-les-Mouli- 
neaux.  Aeroplane  flights  have  been  made  in  Japan,  India, 
Peru,  and  China. 

One  of  the  most  spectacular  of  recent  achievements  is 
that  of  Renaux,  competing  for  the  Michelin  Grand  Prize. 
A  purse  of  $20,000  was  offered  in  1909  by  M.  Michelin,  the 
French  tire  manufacturer,  for  the  first  successful  flight 
from  Paris  to  Clermont-Ferrand  —  260  miles  —  in  less 
than  six  hours.  The  prize  was  to  stand  for  ten  years.  It 
was  prescribed  that  the  aviator  must,  at  the  end  of  the 
journey,  circle  the  tower  of  the  Cathedral  and  alight  on 
the  summit  of  the  Puy  de  Dome  —  elevation  4500  feet  — 
on  a  landing  place  measuring  only  40  by  100  yards,  sur- 
rounded by  broken  and  rugged  ground  and  usually  obscured 
by  fog. 

The  flight  was  attempted  last  year  by  Weymann,  who 
fell  short  of  the  goal  by  only  a  few  miles.  Leon  Morane 
met  with  a  serious  accident,  a  little  later,  while  attempting 
the  trip  with  his  brother  as  a  passenger.  Renaux  completed 
the  journey  with  ease  in  his  Farman  biplane,  carrying  a 
passenger,  his  time  being  308  minutes. 

This  Michelin  Grand  Prize  is  not  to  be  confused  with  the 


Some  Aeroplanes  —  Some  Accomplishments        169 

Michelin  Trophy  of  $4000  offered  yearly  for  the  longest 
flight  in  a  closed  circuit. 

Speeds  have  increased  50%  during  the  past  year;  even 
with  passengers,  machines  have  moved  more  than  a  mile 
a  minute:  average  motor  capacities  have  been  doubled 
or  tripled.  The  French  men  and  machines  hold  the  rec- 
ords for  speed,  duration,  distance,  and  (perhaps)  altitude. 
The  highest  altitude  claimed  is  probably  that  attained  by 
Garros  at  Mexico  City,  early  this  year  —  12,052  feet  above 
sea  level.  The  world's  speed  record  for  a  two-man  flight 
appears  to  be  that  of  Foulois  and  Parmalee,  made  at  Laredo, 
Texas,  March  3,  1911:  106  miles,  cross-country,  in  127  min- 
utes. Three-fourths  of  all  flights  made  up  to  this  time  have 
been  made  in  France  —  a  fair  proportion,  however,  in 
American  machines. 

NOTE 

The  rapidity  with  which  history  is  made  in  aeronautics  is  forci- 
bly suggested  by  the  revision  of  text  made  necessary  by  recent 
news.  The  new  Deutschland  has  met  the  fate  of  its  predecessors; 
the  Paris-Rome-Turin  flight  is  at  this  moment  under  way;  and 
Lieutenant  Bayne,  attempting  once  more  his  France-to-Corsica 
flight,  has  —  for  the  time  being  at  least  —  disappeared. 


THE    POSSIBILITIES    IN   AVIATION 

MEN  now  fly  and  will  probably  keep  on  flying;  but  avia- 
tion is  still  too  hazardous  to  become  the  popular  sport  of 
the  average  man.  The  overwhelmingly  important  prob- 
lem with  the  aeroplane  is  that  of  stability.  These  machines 
must  have  a  better  lateral  balance  when  turning  corners 
or  when  subjected  to  wind  gusts:  and  the  balance  must 
be  automatically,  not  manually,  produced. 


BLANC  MONOPLANE 

Other  necessary  improvements  are  of  minor  urgency  and 
in  some  cases  will  be  easy  to  accomplish.  Better  mechan- 
ical construction,  especially  in  the  details  of  attachments, 
needs  only  persistence  and  common  sense.  Structural 
strength  will  be  increased;  the  wide  spread  of  wing  pre- 
sents difficulties  here,  which  may  be  solved  either  by 

170 


The  Possibilities  in  Aviation 


171 


increasing  the  number  of  superimposed  surfaces,  as  in  tri- 
planes,  or  in  some  other  manner.     Greater  carrying  capac- 


MELVIN  VANIMAN  TRIPLANE 


ity  —  two  men  instead  of  one  —  may  be  insisted  upon: 
and  this  leads  to  the  difficult  question  of  motor  weights. 
The  revolving  air-cooled  motor  may  offer  further  possibil- 


\\ 


JEAN  DE  CRAWHEZ  TRIPLANE 

ities :  the  two-cycle  idea  will  help  if  a  short  radius  of  action 
is  permissible:  but  a  weight  of  less  than  two  pounds  to 


172  Flying  Machines  Today 

the  horse-power  seems  to  imply,  almost  essentially,  a  lack 
of  ruggedness  and  surety  of  operation.     A  promising  field 


for  investigation  is  in  the  direction  of  increasing  propeller 
efficiencies.  If  such  an  increase  can  be  effected,  the  whole 
of  the  power  difficulty  will  be  greatly  simplified. 


The  Possibilities  in  Aviation  173 

This  same  motor  question  controls  the  proposal  for 
increased  speed.  The  use  of  a  reserve  motor  would  again 
increase  weights;  though  not  necessarily  in  proportion  to 
the  aggregate  engine  capacity.  Perhaps  something  may 
be  accomplished  with  a  gasoline  turbine,  when  one  is 
developed.  In  any  case,  no  sudden  increase  in  speeds 
seems  to  be  probable;  any  further  lightening  of  motors 
must  be  undertaken  with  deliberation  and  science.  If 
much  higher  maximum  speeds  are  attained,  there  will  be 
an  opportunity  to  vary  the  speed  to  suit  the  requirements. 
Then  clutches,  gears,  brakes,  and  speed-changing  devices 
of  various  sorts  will  become  necessary,  and  the  problem  of 
weights  of  journal  bearings  —  already  no  small  matter  — 
will  be  made  still  more  serious.  And  with  variable  speed 
must  probably  come  variable  sail  area  —  in  preference  to 
tilting  —  so  that  the  fabric  must  be  reefed  on  its  frame. 
Certainly  two  men,  it  would  seem,  will  be  needed! 

Better  methods  for  starting  are  required.  The  hydro- 
plane idea  promises  much  in  this  respect.  With  a  better 
understanding  and  control  of  the  conditions  associated 
with  successful  and  safe  descent  —  perhaps  with  improved 
appliances  therefor  —  the  problem  of  ascent  will  also  be 
partly  solved.  If  such  result  can  be  achieved,  these 
measures  of  control  must  be  made  automatic. 

The  building  of  complete  aeroplanes  to  standard  designs 
would  be  extremely  profitable  at  present  prices,  which 
range  from  $2500  to  $5000.  Perhaps  the  most  profitable 
part  would  be  in  the  building  of  the  motor.  The  framing 


174  Flying  Machines  Today 

and  fabric  of  an  ordinary  monoplane  could  easily  be  con- 
structed at  a  cost  below  $300.  The  propeller  may  cost 
$50  more.  The  expense  for  wires,  ropes,  etc.,  is  trifling; 
and  unless  special  scientific  instruments  and  accessories 
are  required,  all  of  the  rest  of  the  value  lies  in  the  motor 
and  its  accessories.  Within  reasonable  limits,  present  costs 
of  motors  vary  about  with  the  horse-power.  The  amateur 
designer  must  therefore  be  careful  to  keep  down  weight  and 
power  unless  he  proposes  to  spend  money  quite  freely. 

THE  CASE  OF  THE  DIRIGIBLE 

Not  very  much  is  being  heard  of  performances  of  diri- 
gible balloons  just  at  present.  They  have  shown  them- 
selves to  be  lacking  in  stanchness  and  effectiveness  under 
reasonable  variations  of  weather.  We  must  have  fabrics 
that  are  stronger  for  their  weight  and  more  impervious. 
Envelopes  must  be  so  built  structurally  as  to  resist  deforma- 
tion at  high  speeds,  without  having  any  greatly  increased 
weight.  A  cheap  way  of  preparing  pure  hydrogen  gas 
is  to  be  desired. 

Most  important  of  all,  the  balloon  must  have  a  higher 
speed,  to  make  it  truly  dirigible.  This,  with  sufficient 
steering  power,  will  protect  it  against  the  destructive 
accidents  that  have  terminated  so  many  balloon  careers. 
Here  again  arises  the  whole  question  of  power  in  relation 
to  motor  weight,  though  not  as  formidably  as  is  the  case 
with  the  aeroplane.  The  required  higher  speeds  are  pos- 
sible now,  at  the  cost  merely  of  careful  structural  design, 


The  Possibilities  in  Aviation 


175 


reduced  radius  of  action,  and  reduced  passenger  carrying 
capacity. 

Better  altitude  control  will  be  attained  with  better  fab- 
rics and  the  use  of  plane  fin  surfaces  at  high  speeds.  The 
employment  of  a  vertically-acting  propeller  as  a  somewhat 
wasteful  but  perhaps  finally  necessary  measure  of  safety 
may  also  be  regarded  as  probable. 


GIRAUDON'S  WHEEL  AEROPLANE 

THE  ORTHOPTER 

The  aviplane,  ornithoptere  or  orthopter  is  a  flying  machine 
with  bird-like  flapping  wings,  which  has  received  occa- 
sional attention  from  time  to  time,  as  the  result  of  a  too 
blind  adherence  to  Nature's  analogies.  Every  mechanical 
principle  is  in  favor  of  the  screw  as  compared  with  any 
reciprocating  method  of  propulsion.  There  have  been 
few  actual  examples  of  this  type:  a  model  was  exhibited 
at  the  Grand  Central  Palace  in  New  York  in  January  of 
this  year. 


176  Flying  Machines  Today 

The  mechanism  of  an  orthopter  would  be  relatively 
complex,  and  the  flapping  wings  would  have  to  " feather" 
on  their  return  stroke.  The  flapping  speed  would  have  to 
be  very  high  or  the  surface  area  very  great.  This  last 
requirement  would  lead  to  structural  difficulties.  Pro- 
pulsion would  not  be  uniform,  unless  additional  compli- 
cations were  introduced.  The  machine  would  be  the  most 
difficult  of  any  type  to  balance.  The  motion  of  a  bird's 
wing  is  extremely  complicated  in  its  details  —  one  that  it 
would  be  as  difficult  to  imitate  in  a  mechanical  device  as 
it  would  be  for  us  to  obtain  the  structural  strength  of  an 
eagle's  wing  in  fabric  and  metal,  with  anything  like  the 
same  extent  of  surface  and  limit  of  weight.  According  to 
Pettigrew,  the  efficiency  of  bird  and  insect  flight  depends 
largely  upon  the  elasticity  of  the  wing.  Chatley  gives  the 
ratio  of  area  to  weight  as  varying  from  fifty  (gnat)  to 
one-half  (Australian  crane)  square  feet  per  pound.  The 
usual  ratio  in  aeroplanes  is  from  one-third  to  one-half. 

About  the  only  advantages  perceptible  with  the  orthop- 
ter type  of  machine  would  be,  first,  the  ability  "to  start 
from  rest  without  a  preliminary  surface  glide";  and  sec- 
ond, more  independence  of  irregularity  in  air  currents, 
since  the  propulsive  force  is  exerted  over  a  greater  extent 
than  is  that  of  a  screw  propeller. 

THE  HELICOPTER 

The  gyroplane  or  helicopter  was  the  type  of  flying  machine 
regarded  by  Lord  Kelvin  as  alone  likely  to  survive.  It 


178  Flying  Machines  Today 

lifts  itself  by  screw  propellers  acting  vertically.  This 
form  was  suggested  in  1852.  When  only  a  single  screw 
was  used,  the  whole  machine  rotated  about  its  vertical 
axis.  It  was  attempted  to  offset  this  by  the  use  of  vertical 
fin-planes:  but  these  led  to  instability  in  the  presence  of 
irregular  air  currents.  One  early  form  had  two  oppositely- 
pitched  screws  driven  by  a  complete  steam  engine  and 
boiler  plant.  One  of  the  Cornu  helicopters  had  adjustable 
inclined  planes  under  the  two  large  vertically  propelling 
screws.  The  air  which  slipped  past  the  screws  imposed 
a  pressure  on  the  inclined  planes  which  was  utilized  to 
produce  horizontal  movement  in  any  desired  direction  — 
if  the  wind  was  not  too  adverse.  A  gasoline  engine  was 
carried  in  a  sort  of  well  between  the  screws. 

The  helicopter  may  be  regarded  as  the  limiting  type  of 
aeroplane,  the  sail  area  being  reduced  nearly  to  zero;  the 
wings  becoming  mere  fins,  the  smaller  the  better.  It 
therefore  requires  maximum  motor  power  and  is  particu- 
larly dependent  upon  the  development  of  an  excessively 
light  motor.  It  is  launched  and  descends  under  perfect 
control,  without  regard  to  horizontal  velocity.  It  has 
very  little  exposed  surface  and  is  therefore  both  easy  to 
steer  and  independent  of  wind  conditions.  By  properly 
arranging  the  screws  it  can  be  amply  balanced:  but  it  must 
have  a  particularly  stout  and  strong  frame. 

The  development  of  this  machine  hinges  largely  on  the 
propeller.  It  is  not  only  necessary  to  develop  power 
(which  means  force  multiplied  by  velocity)  but  actual 


The  Possibilities  in  Aviation  179 

propulsive  vertical  force:  and  this  must  exceed  or  at  least 
equal  the  whole  weight  of  the  machine.  From  ten  to 
forty  pounds  of  lifting  force  per  horse-power  have  been 
actually  attained:  and  with  motors  weighing  less  than  five 
pounds  there  is  evidently  some  margin.  The  propellers 
are  of  special  design,  usually  with  very  large  blades.  Four 
are  commonly  used:  one,  so  to  speak,  at  each  " corner" 
of  the  machine.  The  helicopter  is  absolutely  dependent 
upon  its  motors.  It  cannot  descend  safely  if  the  power 
fails.  If  it  is  to  do  anything  but  ascend  and  descend  it 
must  have  additional  propulsive  machinery  for  producing 
horizontal  movement. 

COMPOSITE  TYPES 

The  aeroplane  is  thus  particularly  weak  as  to  stability, 
launching,  and  descending:  but  it  is  economical  in  power 
because  it  uses  the  air  to  hold  itself  up.  The  dirigible 
balloon  is  lacking  in  power  and  speed,  but  can  ascend  and 
descend  safely,  even  if  only  by  wasteful  methods;  and  it 
can  carry  heavy  weights,  which  are  impossible  with  the 
structurally  fragile  aeroplane.  The  helicopter  is  waste- 
ful in  power,  but  is  stable  and  sure  in  ascending  and 
descending,  providing  only  that  the  motor  power  does  not 
fail. 

Why,  then,  not  combine  the  types?  An  aeroplane- 
dirigible  would  be  open  to  only  one  objection:  on  the 
ground  of  stability.  The  dirigible-helicopter  would  have 
as  its  only  disadvantage  a  certain  wastefulness  of  power, 


180  Flying  Machines  Today 

while   the   aeroplane-helicopter  would    seem   to   have   no 
drawback  whatever. 

All  three  combinations  have  been,  or  are  being,  tried. 
An  Italian  engineer  officer  has  designed  a  balloon-aero- 
plane. The  balloon  is  greatly  flattened,  or  lens-shaped, 
and  floats  on  its  side,  presenting  its  edge  to  the  horizon  - 
if  inclination  be  disregarded.  With  some  inclination,  the 
machine  acts  like  an  aeroplane  and  is  partially  self-sustain- 
ing at  any  reasonable  velocity. 

The  use  of  a  vertically-acting  screw  on  a  dirigible  com- 
bines the  features  of  that  type  and  the  helicopter.  This 
arrangement  has  also  been  the  subject  of  design  (as  in 
Captain  Miller's  flexible  balloon)  if  not  of  construction. 
The  combination  of  helicopter  and  aeroplane  seems  espe- 
cially promising:  the  vertical  propellers  being  employed  for 
starting  and  descending,  as  an  emergency  safety  feature 
and  perhaps  for  aicf  in  stabilizing.  The  fact  that  composite 
types  of  flying  machine  have  been  suggested  is  perhaps, 
however,  an  indication  that  the  ultimate  type  has  not 
yet  been  established. 

WHAT  is  PROMISED 

The  flying  machine  will  probably  become  the  vehicle 
of  the  explorer.  If  Stanley  had  been  able  to  use  a  small 
high-powered  dirigible  in  the  search  for  Livingstone,  the 
journey  would  have  been  one  of  hours  as  compared  with 
months,  the  food  and  general  comfort  of  the  party  would 
have  been  equal  in  quality  to  those  attainable  at  home, 


The  Possibilities  in  Aviation  181 

and    the    expense  in  money   and  in   human   life   would 
have  been  relatively  trifling. 

Most  readers  will  remember  the  fate  of  Andree,  and  the 
projected  polar  expeditions  of  Wellman  in  1907  and  1909. 
Misfortune  accompanied  both  attempts;  but  one  has  only 
to  read  Peary's  story  of  the  dogged  tramp  over  the  Green- 


WELLMAN'S  AMERICA 
(From  Wellman's  Aerial  Age) 

land  ice  blink  to  realize  that  danger  and  misfortune  in 
no  less  degree  have  accompanied  other  plans  of  Arctic 
pioneering.  With  proper  design  and  the  right  men,  it 
does  not  seem  unreasonable  to  expect  that  a  hundred 
flying  machines  may  soar  above  Earth's  invisible  axial 
points  during  the  next  dozen  years.* 

*The  high  wind  velocities  of  the  southern  circumpolar  regions  may  be 
an  insurmountable  obstacle  in  the  Antarctic.  Yet  Mawson  expects  to 
take  with  him  a  2-passenger  monoplane  having  a  i8o-mile  radius  of  action 
on  the  expedition  proposed  for  this  year. 


1 82  Flying  Machines  Today 

The  report  of  Count  Zeppelin's  Spitzbergen  expedi- 
tion of  last  year  has  just  been  made  public.  This 
was  undertaken  to  ascertain  the  adaptability  of  flying 
machines  for  Arctic  navigation.  Besides  speed  and  ra- 
dius of  action,  the  conclusive  factors  include  that  of 
freedom  from  such  breakdowns  as  cannot  be  made  good 
on  the  road. 

For  exploration  in  other  regions,  the  balloon  or  the  aero- 
plane is  sure  to  be  employed.  Rapidity  of  progress  with- 
out fatigue  or  danger  will  replace  the  floundering  through 
swamps,  shivering  with  ague,  and  bickering  with  hostile 
natives  now  associated  with  tropical  and  other  expeditions. 
The  stereoscopic  camera  with  its  scientific  adjuncts  will 
permit  of  almost  automatic  map-making,  more  compre- 
hensive and  accurate  than  any  now  attempted  in  other 
than  the  most  settled  sections.  It  is  not  too  much  to 
expect  that  arrangements  will  be  perfected  for  conducting 
complete  topographical  surveys  without  more  than  occa- 
sional descents.  If  extremely  high  altitudes  must  be 
attained  —  over  a  mile  —  the  machines  will  be  of  special 
design;  but  as  far  as  can  now  be  anticipated,  there  will 
be  no  insurmountable  difficulties.  The  virgin  peaks  of 
Ruwenzori  and  the  Himalayas  may  become  easily  access- 
ible —  even  to  women  and  children  if  they  desire  it.  We 
may  obtain  direct  evidence  as  to  the  contested  ascent  of 
Mt.  McKinley.  A  report  has  been  current  that  a  Bleriot 
monoplane  has  been  purchased  for  use  in  the  inspection 
of  construction  work  for  an  oil  pipe  line  across  the  Persian 


The  Possibilities  in  Aviation  183 

desert;   the  aeroplane  being   regarded   as   "more   expedi- 
tious and  effectual"  than  an  automobile. 

The  flying  machine  is  the  only  land  vehicle  which 
requires  no  "permanent  way."  Trains  must  have  rails, 
bicycles  and  automobiles  must  have  good  roads.  Even 
the  pedestrian  gets  along  better  on  a  path.  The  ships  of 
the  air  and  the  sea  demand  no  improvement  of  the  fluids 
in  which  they  float.  To  carry  mails,  parcels,  persons,  and 
even  light  freight  —  these  applications,  if  made  commer- 
cially practicable  tomorrow,*  would  surprise  no  one;  their 
possibility  has  already  been  amply  demonstrated.  With 
the  dirigible  as  the  transatlantic  liner  and  the  aeroplane 
as  the  naphtha  launch  of  the  air,  the  whole  range  of  appli- 
cations is  commanded.  Hangars  and  landing  stages  - 
the  latter  perhaps  on  the  roofs  of  buildings,  revolutioniz- 
ing our  domestic  architecture  —  may  spring  up  as  rapidly 
as  garages  have  done.  And  the  aeroplane  is  potentially 
(with  the  exception  of  the  motorcycle)  the  cheapest  of 
self-propelled  vehicles. 

Governments  have  already  considered  the  possibilities 
of  aerial  smuggling.  Perhaps  our  custom-house  officers 
will  soon  have  to  watch  a  fence  instead  of  a  line:  to  barri- 
cade in  two  dimensions  instead  of  one.  They  will  need 
to  be  provided  with  United  States  Revenue  aeroplanes. 
But  how  are  aerial  frontiers  to  be  marked?  And  does  a 


*  It  seems  that  tomorrow  has  come;  for  an  aeroplane  is  being  regu- 
larly used  (according  to  a  reported  interview  wjth  Dr.  Alexander  Graham 
Bell)  for  carrying  mails  in  India. 


184  Flying  Machines  Today 

nation  own  the  air  above  it,  or  is  this,  like  the  high  seas, 
"by  natural  right,  common  to  all"  ?  Can  a  flying-machine 
blockade-runner  above  the  three-mile  height  claim  extra- 
territoriality? 

The  flying  machine  is  no  longer  the  delusion  of  the 
"crank,"  because  it  has  developed  a  great  industry.  A 
now  antiquated  statement  put  the  capitalization  of  aero- 
plane manufactories  in  France  at  a  million  dollars,  and  the 
development  expenditure  to  date  at  six  millions.  There 
are  dozens  of  builders,  in  New  York  City  alone,  of  mono- 
planes, biplanes,  gliders,  and  models.  A  permanent  exhi- 
bition of  air  craft  is  just  being  inaugurated.  We  have  now 
even  an  aeronautic  "trust,"  since  the  million-dollar  cap- 
italization of  the  Maxim,  Bleriot,  Grahame- White  firm. 

According  to  the  New  York  Sun,  over  $500,000  has  been 
subscribed  for  aviation  prizes  in  1911.  The  most  valuable 
prizes  are  for  new  records  in  cross-country  flights.  The 
Paris  Journal  has  offered  $70,000  for  the  best  speed  in  a 
circling  race  from  Paris  to  Berlin,  Brussels,  London,  and 
back  to  Paris — 1500  miles.  Supplementary  prizes  from 
other  sources  have  increased  the  total  stake  in  this  race  to 
$100,000.  A  purse  of  $50,000  is  offered  by  the  London 
Daily  Mail  for  the  "Circuit  of  Britain"  race,  from  London 
up  the  east  coast  to  Edinburgh,  across  to  Glasgow,  and 
home  by  way  of  the  west  coast,  Exeter,  and  the  Isle  of 
Wight;  a  thousand  miles,  to  be  completed  in  two  weeks, 
beginning  July  22,  with  descents  only  at  predetermined 
points.  This  contest  will  be  open  (at  an  entrance  fee  of 


The  Possibilities  in  Aviation  185 

$500)  to  any  licensee  of  the  International  Federation.  A 
German  circuit,  from  Berlin  to  Bremen,  Magdeburg,  Diissel- 
dorf,  Aix-la-Chapelle,  Dresden,  and  back  to  the  starting 
point,  is  proposed  by  the  Zeitung  am  Mittag  of  Berlin,  a 
prize  of  $25,000  having  been  offered.  In  this  country,  a 
comparatively  small  prize  has  been  established  for  a  run 
from  San  Francisco  to  New  York,  ma  Chicago.  Besides  a 
meet  at  Bridgeport,  May  18-20,  together  with  those  to  be 
held  by  several  of  the  colleges  and  the  ones  at  Bennings 
and  Chicago,  there  will  be,  it  is  still  hoped,  a  national 
tournament  at  Belmont  Park  at  the  end  of  the  same  month. 
Here  probably  a  dozen  aviators  will  contest  in  qualification 
for  the  international  meet  in  England,  to  which  three 
American  representatives  should  be  sent  as  competitors 
for  the  championship  trophy  now  held  by  Mr.  Grahame- 
White.  It  is  anticipated  that  the  chances  in  the  inter- 
national races  favor  the  French  aviators,  some  of  whom  — • 
in  particular,  Leblanc  —  have  been  making  sensational 
records  at  Pau.  Flights  between  aviation  fields  in  different 
cities  are  the  leading  feature  in  the  American  program  for 
the  year.  A  trip  is  proposed  from  Washington  to  Belmont 
Park,  via  Atlantic  City,  the  New  Jersey  coast,  and  lower 
New  York  bay.  The  distance  is  250  miles  and  the  time 
will  probably  be  less  than  that  of  the  best  passenger  trains 
between  Washington  and  New  York.  If  held,  this  race 
will  probably  take  place  late  in  May.  It  is  wisely  concluded 
that  the  advancement  of  aviation  depends  upon  cross- 
country runs  under  good  control  and  at  reasonable  speeds 


1 86  Flying  Machines  Today 

and  heights  rather  than  upon  exhibition  flights  in  enclo- 
sures. It  is  to  be  hoped  that  commercial  interests  will  not 
be  sufficiently  powerful  to  hinder  this  development. 

We  shall  of  course  have  the  usual  international  champion- 
ship balloon  race,  preceded  by  elimination  contests.  From 
present  indications  Omaha  is  likely  to  be  chosen  as  the 
point  of  departure. 

The  need  for  scientific  study  of  aerial  problems  is 
recognized.  The  sum  of  $350,000  Jias  been  offered  the 
University  of  Paris  to  found  an  aeronautic  institute.  In 
Germany,  the  university  at  Gottingen  has  for  years  main- 
tained an  aerodynamic  laboratory.  Lord  Rayleigh,  in 
England,  is  at  the  head  of  a  committee  of  ten  eminent 
scientists  and  engineers  which  has,  under  the  authority 
of  Parliament,  prepared  a  program  of  necessary  theoret- 
ical and  experimental  investigations  in  aerostatics  and  aero- 
dynamics. Our  American  colleges  have  organized  student 
aviation  societies  and  in  some  of  them  systematic  instruc- 
tion is  given  in  the  principles  underlying  the  art.  A  per- 
manent aeronautic  laboratory,  to  be  located  at  Washington, 
D.C.,  is  being  promoted. 

Aviation  as  a  sport  is  under  the  control  of  the  Interna- 
tional Aeronautic  Federation,  having  its  headquarters  at 
Paris.  Bodies  like  the  Royal  Aero  Club  of  England  and 
the  Aero  Club  of  America  are  subsidiaries  to  the  Federation. 
In  addition,  we  have  in  this  country  other  clubs,  like 
the  Aeronautic  Society,  the  United  States  Aeronautical 
Reserve,  etc.  The  National  Council  of  the  Aero  Clubs  of 


The  Possibilities  in  Aviation  187 

America  is  a  sort  of  supreme  court  for  all  of  these,  having 
control  of  meets  and  contests;  but  it  has  no  affiliation 
with  the  International  body,  which  is  represented  here  by 
the  Aero  Club  of  America.  The  Canadian  Auto  and  Aero 
Club  supervises  aviation  in  the  Dominion 

Aviation  has  developed  new  legal  problems:  problems 
of  liability  for  accidents  to  others;  the  matter  of  super- 
vision of  airship  operators.  Bills  to  license  and  regulate 
air  craft  have  been  introduced  in  at  least  two  state  legis- 
latures. 

Schools  for  instruction  in  flying  as  an  art  or  sport  are 
being  promoted.  It  is  understood  that  the  Wright  firm 
is  prepared  to  organize  classes  of  about  a  dozen  men,  sup- 
plying an  aeroplane  for  their  instruction.  Each  man  pays 
a  small  fee,  which  is  remitted  should  he  afterward  pur- 
chase a  machine.  Mr.  Grahame- White,  at  Pau,  in  the 
south  of  France,  conducts  a  school  of  aviation,  and  the 
arrangements  are  now  being  duplicated  in  England.  In- 
struction is  given  on  Bleriot  monoplanes  and  Farman 
biplanes,  at  a  cost  of  a  hundred  guineas  for  either.  The 
pupil  is  coached  until  he  can  make  a  three-mile  flight; 
meanwhile,  he  is  held  partially  responsible  for  damage 
and  is  required  to  take  out  a  "  third-party "  insurance 
policy. 

There  is  no  lack  of  aeronautic  literature.  Major  Squier's 
paper  in  the  Transactions  of  the  American  Society  of 
Mechanical  Engineers,  1908,  gave  an  eighteen-page  list 
of  books  and  magazine  articles  of  fair  completeness  up 


1 88  Flying  Machines  Today 

to  its  date;  Professor  Chatley's  book,  Aeroplanes,  1911, 
discusses  some  recent  publications;  the  Brooklyn  Public 
Library  in  New  York  issued  in  1910  (misdated  1909)  a 
manual  of  fourteen  pages  critically  referring  to  the  then 
available  literature,  and  itself  containing  a  list  of  some 
dozen  bibliographies. 


AERIAL  WARFARE 

THE  use  of  air  craft  as  military  auxiliaries  is  not  new. 
As  early  as  1812  the  Russians,  before  retreating  from  Mos- 
cow, attempted  to  drop  bombs  from  balloons:  an  attempt 
carried  to  success  by  Austrian  engineers  in  1849. 


(Photo  by  Paul  Thompson) 

contestants  in  our  own  War  of  Secession  employed  captive 
and  drifting  balloons.  President  Lincoln  organized  a 
regular  aeronautic  auxiliary  staff  in  which  one  Lowe  held 
the  official  rank  of  chief  aeronaut.  This  same  gentleman 
(who  had  accomplished  a  reconnaissance  of  350  miles  in 

eight  hours  in  a  25,000  cubic  foot  drifting  balloon)  was 

189 


190  Flying  Machines  Today 

subjected  to  adverse  criticism  on  account  of  a  weakness 
for  making  ascents  while  wearing  the  formal  "  Prince 
Albert"  coat  and  silk  hat!  A  portable  gas-generating 
plant  was  employed  by  the  Union  army.  We  are  told 
that  General  Stoneman,  in  1862,  directed  artillery  fire 
from  a  balloon,  which  was  repeatedly  fired  at  by  the 
enemy,  but  not  once  hit.  The  Confederates  were  less 
amply  equipped.  Their  balloon  was  a  patchwork  of  silk 
skirts  contributed  (one  doubts  not,  with  patriotic  alacrity) 
by  the  daughters  of  the  Confederacy. 

It  is  not  forgotten  that  communication  between  be- 
sieged Paris  and  the  external  world  was  kept  up  for  some 
months  during  1870-71  by  balloons  exclusively.  Mail 
was  carried  on  a  truly  commercial  scale:  pet  animals 
and  —  the  anticlimax  is  unintended  —  164  persons,  includ- 
ing M.  Gambetta,  escaped  in  some  sixty-five  flights. 
Balloons  were  frequently  employed  in  the  Franco-Prussian 
contest;  and  they  were  seldom  put  hors  de  combat  by  the 
enemy. 

During  our  war  with  Spain,  aerial  craft  were  employed 
in  at  least  one  instance,  namely,  at  San  Juan,  Porto  Rico, 
for  reconnoitering  entrenchments.  Frequent  ascents  were 
made  from  Ladysmith,  during  the  Boer  war.  The  balloons 
were  often  fired  at,  but  never  badly  damaged.  Cronje's 
army  was  on  one  occasion  located  by  the  aid  of  a  British 
scout-balloon.  Artillery  fire  was  frequently  directed  from 
aerial  observations.  Both  sides  employed  balloons  in 
the  epic  conflict  between  Russia  and  Japan. 


Aerial  Warfare  191 

A  declaration  introduced  at  the  second  international 
peace  conference  at  the  Hague  proposed  to  prohibit,  for 
a  limited  period,  the  discharge  of  projectiles  or  explosives 
from  flying  machines  of  any  sort.  The  United  States  was 
the  only  first-class  power  which  endorsed  the  declaration. 
It  does  not  appear  likely,  therefore,  that  international  law 
will  discountenance  the  employment  of  aerial  craft  in 
international  disputes.  The  building  of  airships  goes  on 
with  increasing  eagerness.  Last  year  the  Italian  chamber 
appropriated  $5,000,000  for  the  construction  and  mainte- 
nance of  flying  machines. 

A  press  report  dated  February  4  stated  that  a  German 
aeronaut  had  been  spending  some  weeks  at  Panama, 
studying  the  air  currents  of  the  Cana]  Zone.  No  flying 
machine  may  in  Germany  approach  more  closely  than 
within  six  miles  of  a  fort,  unless  specially  licensed.  At 
the  Krupp  works  in  Essen  there  are  being  tested  two 
new  guns  for  shooting  at  aeroplanes  and  dirigibles.  One 
is  mounted  on  an  armored  motor  truck.  The  other  is  a 
swivel-mounted  gun  on  a  flat-topped  four-wheeled  carriage. 

The  United  States  battleship  Connecticut  cost  $9,000,000. 
It  displaces  18,000  tons,  uses  17,000  horse-power  and 
1000  men,  and  makes  twenty  miles  an  hour.  An  aero- 
plane of  unusual  size  with  nearly  three  times  this  speed, 
employing  from  one  to  three  men  with  an  engine  of  100 
horse-power,  would  weigh  one  ton  and  might  cost  $5000. 
A  Dreadnought  costs  $16,000,000,  complete,  and  may  last 
—  it  is  difficult  to  say,  but  few  claim  more  than  ten 


1 92  Flying  Machines  Today 

years.  It  depreciates,  perhaps,  at  the  rate  of  $2,000,000  a 
year.  Aeroplanes  built  to  standard  designs  in  large  quan- 
tities would  cost  certainly  not  over  $1000  each.  The 
ratio  of  cost  is  16,000  to  i.  Would  the  largest  Dread- 
nought, exposed  unaided  to  the  attack  of  16,000  flying 
machines,  be  in  an  entirely  enviable  situation? 

An  aeroplane  is  a  fragile  and  costly  thing  to  hazard  at 
one  blow:  but  not  more  fragile  or  costly  than  a  Whitehead 
torpedo.  The  aeroplane  soldier  takes  tremendous  risks; 
but  perhaps  not  greater  risks  than  those  taken  by  the  crew 
of  a  submarine.  There  is  never  any  lack  of  daring  men 
when  daring  is  the  thing  needed. 

All  experience  goes  to  show  that  an  object  in  the  air  is 
hard  to  hit.  The  flying  machine  is  safer  from  attack 
where  it  works  than  it  is  on  the  ground.  The  aim  neces- 
sary to  impart  a  crippling  blow  to  an  aeroplane  must  be 
one  of  unprecedented  accuracy.  The  dirigible  balloon 
gives  a  larger  mark,  but  could  not  be  immediately  crippled 
by  almost  any  projectile.  It  could  take  a  good  pounding 
and  still  get  away.  Interesting  speculations  might  be  made 
as  to  the  outcome  of  an  aerial  battle  between  the  two  types 
of  craft.  The  aeroplane  might  have  a  sharp  cutting 
beak  with  which  to  ram  its  more  cumbersome  adversary, 
but  this  would  involve  some  risk  to  its  own  stability:  and 
the  balloon  could  easily  escape  by  a  quick  ascent.  It  has 
been  suggested  that  each  dirigible  would  need  an  aero- 
plane escort  force  for  its  defense  against  ramming.  Any 
collision  between  two  opposing  heavier-than-air  machines 


Aerial  Warfare  193 

could  not,  it  would  seem,  be  other  than  disastrous:  but 
perhaps  the  dirigible  could  rescue  the  wrecks.  Possibly 
gas-inflated  life  buoys  might  be  attached  to  the  individual 
combatants.  In  the  French  manceuvers,  a  small  aero- 
plane circled  the  dirigible  with  ease,  flying  not  only  around 
it,  but  in  vertical  circles  over  and  under  it. 


7.5  CENTIMETER  GERMAN  AUTOMATIC  GUN  FOR  ATTACKING  AIRSHIPS 
(From  Brewer's  Art  of  Aviation) 

The  French  war  office  has  exploited  both  types  of 
machine.  In  Germany,  the  dirigible  has  until  recently 
received  nearly  all  the  attention  of  strategists:  but  the 
results  of  a  recent  aerial  war  game  have  apparently  sug- 
gested a  change  in  policy,  and  the  Germans  are  now, 


1 94  Flying  Machines  Today 

without  neglecting  the  balloon,  actively  developing  its 
heavier-than-air  competitor.  England  seems  to  be  muddled 
as  to  its  aerial  policy,  while  the  United  States  has  been 
waiting  and  for  the  most  part  doing  nothing.  Now,  how- 
ever, the  mobilizations  in  Texas  have  been  associated  with 
a  considerable  amount  of  aeroplane  enthusiasm.  A  half- 
dozen  machines,  it  is  expected,  will  soon  be  housed  in  the 
aerodrome  at  San  Antonio.  Experiments  are  anticipated 
in  the  carrying  of  light  ammunition  and  emergency  supplies, 
and  one  of  the  promised  manceuvers  is  to  be  the  locating 
of  concealed  bodies  of  troops  by  air  scouts.  Thirty  army 
officers  are  to  be  detailed  for  aeroplane  service  this  year; 
five  training  schools  are  to  be  established. 

If  flying  machines  are  relatively  unsusceptible  to  attack, 
there  is  also  some  question  as  to  their  effectiveness  in 
attack.  Rifles  have  been  discharged  from  moving  bal- 
loons with  some  degree  of  accuracy  in  aim;  but  long-range 
marksmanship  with  any  but  hand  weapons  involves  the 
mastery  of  several  difficult  factors  additional  to  those 
present  in  gunnery  at  sea.  The  recoil  of  guns  might 
endanger  stability;  and  it  is  difficult  to  estimate  the 
possible  effects  of  a  powerful  concussion,  with  its  resulting 
surges  of  air,  in  the  immediate  vicinity  of  a  delicately 
balanced  aerial  vessel. 

But  aside  from  purely  combative  functions,  air  craft 
may  be  superlatively  useful  as  messengers.  To  send 
despatches  rapidly  and  without  interference,  or  to  carry 
a  general  100  miles  in  as  many  minutes  —  these  accom- 


Aerial  Warfare  195 

plishments  would  render  impossible  the  romance  of  a 
"  Sheridan's  Ride,"  but  might  have  a  romance  of  their 
own.  With  the  new  sense  added  to  human  equipment  by 
wireless  communication,  the  results  of  observations  may  be 
signaled  to  friends  over  miles  of  distance  without  inter- 
vening permanent  connections  of  however  fragile  a  nature. 
Flying  machines  would  seem  to  be  the  safest  of  scouts. 
They  could  pass  over  the  enemy's  country  with  as  little 
direct  danger  —  perhaps  as  unobserved  —  as  a  spy  in 
disguise;  yet  their  occupants  would  scarcely  be  subjected 
to  the  penalty  accompanying  discovery  of  a  spy.  They 
could  easily  study  the  movements  of  an  opposing  armed 
force:  a  study  now  frequently  associated  with  great  loss 
of  life  and  hampering  of  effective  handling  of  troops. 
They  could  watch  for  hostile  fleets  with  relatively  high 
effectiveness  (under  usual  conditions),  commanding  dis- 
tant approaches  to  a  long  coast  line  at  slight  cost.  From 
their  elevated  position,  they  could  most  readily  detect 
hostile  submarines  threatening  their  own  naval  fleet. 
Maximum  effective  reconnaissance  in  minimum  time  would 
be  their  chief  characteristic:  in  fact,  the  high  speeds  might 
actually  constitute  an  objection,  if  they  interfered  with 
thorough  observation.  But  if  air  craft  had  been  avail- 
able at  Santiago  in  1898,  Lieutenant  Blue's  expedition 
would  have  been  unnecessary,  and  there  would  have  been 
for  no  moment  any  doubt  that  Admiral  Cervera's  fleet 
was  actually  bottled  up  behind  the  Morro.  No  besieged 
fortress  need  any  longer  be  deprived  of  communication 


196  Flying  Machines  Today 

with  —  or  even  some  medical  or  other  supplies  from  - 
its  friends.     Suppose  that  Napoleon  had  been  provided 
with  a  flying  machine  at  Elba  —  or  even  at  St.  Helena! 

The  applications  to  rapid  surveying  of  unknown  ground 
that  have  been  suggested  as  possible  in  civil  life  would 
be  equally  possible  in  time  of  war.  Even  if  the  scene  of 
conflict  were  in  an  unmapped  portion  of  the  enemy's  terri- 
tory, the  map  could  be  quickly  made,  the  location  of  tem- 
porary defenses  and  entrenchments  ascertained,  and  the 
advantage  of  superior  knowledge  of  the  ground  completely 
overcome  prior  to  an  engagement.  The  searchlight  and 
the  compass  for  true  navigation  on  long  flights  over  un- 
known country  would  be  the  indispensable  aids  in  such 
applications. 

During  the  current  mobilization  of  the  United  States 
Army  at  Texas,  a  despatch  was  carried  21  miles  on  a  map- 
and-compass  flight,  the  round  trip  occupying  less  than  two 
hours,  and  being  made  without  incident.  The  machine 
flew  at  a  height  of  1500  feet  and  was  sighted  several  miles 
off. 

A  dirigible  balloon,  it  has  been  suggested,  is  compara- 
tively safe  while  moving  in  the  air,  but  is  subjected  to 
severe  strains  when  anchored  to  the  ground,  if  exposed. 
It  must  have  either  safe  harbors  of  refuge  or  actual  shelter 
buildings  —  dry  docks,  so  to  speak.  In  an  enemy's  coun- 
try a  ravine  or  even  a  deep  railway  cut  might  answer  in  an 
emergency:  but  the  greatest  reliance  would  have  to  be 
placed  on  quick  return  trips  from  a  suitable  base.  The 


Aerial  Warfare 


balloon  would  be,  perhaps,  a  more  effective  weapon  in 
defense  than  in  attack.  Major  Squier  regards  a  flying 
height  of  one  mile  as  giving  reasonable  security  against 
hostile  projectiles  in  the  daytime.  A  lower  elevation 


GERMAN   GUN  FOR  'SHOOTING  AT 

AEROPLANES 
(From  Brewer's  Art  of  Aviation) 

would  be  sufficient  at  night.  Given  a  suitable  telephoto- 
graphic  apparatus,  all  necessary  observations  could  easily 
be  made  from  this  altitude.  Even  in  the  enemy's  territory, 
descent  to  the  earth  might  be  possible  at  night  under  rea- 


198  Flying  Machines  Today 

sonably  favorable  conditions.  Two  sizes  of  balloon  would 
seem  to  be  indicated:  the  scouting  work  described  would 
be  done  by  a  small  machine  having  the  greatest  possible 
radius  of  action.  Frontiers  would  be  no  barrier  to  it. 
Sent  from  England  in  the  night  it  could  hover  over  a  Kiel 
canal  or  an  island  of  Heligoland  at  sunrise,  there  to  observe 
in  most  leisurely  fashion  an  enemy's  mobilizations. 

At  the  London  meeting  of  the  Institute  of  Naval  Archi- 
tects, in  April,  1911,  the  opinion  was  expressed  that  the  only 
effective  way  of  meeting  attack  from  a  flying  machine  at 
sea  would  be  by  a  counter-attack  from  the  same  type  of 
craft.  The  ship  designers  concluded  that  the  aeroplane 
would  no  more  limit  the  sizes  of  battleships  than  the 
torpedo  has  limited  them. 

For  the  more  serious  work  of  fighting,  larger  balloons 
would  be  needed,  with  net  carrying  capacities  perhaps 
upward  from  one  ton.  Such  a  machine  could  launch 
explosives  and  combustibles  against  the  enemy's  forts,  dry 
docks,  arsenals,  magazines,  and  battleships.  It  could  easily 
and  completely  destroy  his  railroads  and  bridges;  perhaps 
even  his  capital  itself,  including  the  buildings  housing  his 
chief  executive  and  war  office  staff.  Nothing  —  it  would 
seem — could  effectually  combat  it  save  air  craft  of  its  own 
kind.  The  battles  of  the  future  may  be  battles  of  the  air. 

There  are  of  course  difficulties  in  the  way  of  dropping 
missiles  of  any  great  size  from  flying  machines.  Curtiss 
and  others  have  shown  that  accuracy  of  aim  is  possible. 
Eight-pound  shrapnel  shells  have  been  dropped  from  an 


Aerial  Warfare 


199 


SANTOS-DUMONT  CIRCLING  THE  EIFFEL  TOWER 
(From  Walker's  Aerial  Navigation) 


2oo  Flying  Machines  Today 

aeroplane  with  measurably  good  effect,  without  upsetting 
the  vessel;  but  at  best  the  sudden  liberation  of  a  consider- 
able weight  will  introduce  stabilizing  and  controlling  diffi- 
culties. The  passengers  who  made  junketing  trips  about 
Paris  on  the  Clement-Bayard  complained  that  they  were 
not  allowed  to  throw  even  a  chicken-bone  overboard!  But 
it  does  not  seem  too  much  to  expect  that  these  purely 
mechanical  difficulties  will  be  overcome  by  purely  mechan- 
ical remedies.  An  automatic  venting  of  a  gas  ballonet 
of  just  sufficient  size  to  compensate  for  the  weight  of  the 
dropped  shell  would  answer  in  a  balloon:  a  similar  auto- 
matic change  in  propeller  speed  and  angle  of  planes  would 
suffice  with  the  aeroplane.  There  is  no  doubt  but  that 
air  craft  may  be  made  efficient  agents  of  destruction  on  a 
colossal  scale. 

A  Swedish  engineer  officer  has  invented  an  aerial  tor- 
pedo, automatically  propelled  and  balanced  like  an  ordi- 
nary submarine  torpedo.  It  is  stated  to  have  an  effective 
radius  of  three  miles  while  carrying  two  and  one-half 
pounds  of  explosive  at  the  speed  of  a  bullet.  One  can  see 
no  reason  why  such  torpedoes  of  the  largest  size  are  not 
entirely  practicable:  though  much  lower  speeds  than  that 
stated  should  be  sufficient. 

According  to  press  reports,  the  Krupps  have  developed 
a  non-recoiling  torpedo,  having  a  range  exceeding  5000 
yards.  The  percussion  device  is  locked  at  the  start,  to 
prevent  premature  explosion:  unlocking  occurs  only  after 
a  certain  velocity  has  been  attained. 


Aerial  Warfare  201 

Major  Squier  apparently  contends  that  the  prohibition 
of  offensive  aerial  operations  is  unfair,  unless  with  it 
there  goes  the  reciprocal  provision  that  a  war  balloon 
shall  not  be  fired  at  from  below.  Again,  there  seems 
to  be  no  good  reason  why  aerial  mines  dropped  from 
above  should  be  forbidden,  while  submarine  mines  — 
the  most  dangerous  naval  weapons  —  are  allowed.  Mod- 
ern strategy  aims  to  capture  rather  than  to  destroy: 
the  manceuvering  of  the  enemy  into  untenable  situations 
by  the  rapid  mobilization  of  troops  being  the  end  of 
present-day  highly  organized  staffs.  Whether  the  dirigi- 
ble (certainly  not  the  aeroplane)  will  ever  become  an 
effective  vehicle  for  transport  of  large  bodies  of  troops 
cannot  yet  be  foreseen. 

Differences  in  national  temper  and  tradition,  and  the 
conflict  of  commercial  enterprise,  perhaps  the  very  recent- 
ness  of  the  growth  of  a  spirit  of  national  unity  on  the  one 
hand,  are  rapidly  bringing  the  two  foremost  powers  of 
Europe  into  keen  competition:  a  competition  which  is 
resulting  in  a  bloodless  revolution  in  England,  necessitated 
by  the  financial  requirements  of  its  naval  program.  Ger- 
many, by  its  strategic  geographical  position,  its  dominating 
military  organization,  and  the  enforced  frugality,  resource- 
fulness, and  efficiency  of  its  people,  possesses  what  must 
be  regarded  as  the  most  invincible  army  in  the  world.  Its 
avowed  purpose  is  an  equally  invincible  navy.  Whether 
the  Gibraltar-Power  can  keep  its  ascendancy  may  well 
be  doubted.  The  one  doubtful  —  and  at  the  same  time 


2O2  Flying  Machines  Today 

perhaps  hopeful  —  factor  lies  in  the  possibilities  of  aerial 
navigation. 

If  one  battleship,  in  terms  of  dollars,  represents  16,000 
airships,  and  if  one  or  a  dozen  of  the  latter  can  destroy  the 


LATHAM,  FARMAN,  AND  PAULHAN 

former  —  a  feat  not  perhaps  beyond  the  bounds  of  pos- 
sibility —  if  the  fortress  that  represents  the  skill  and  labor 
of  generations  may  be  razed  by  twoscore  men  operating 
from  aloft,  then  the  nations  may  beat  their  spears  into 
pruning-hooks  and  their  swords  into  plowshares:  then  the 


Aerial  Warfare  203 

battle  ceases  to  hinge  on  the  power  of  the  purse.  Let 
war  be  made  so  costly  that  nations  can  no  more  afford  it 
than  sane  men  can  wrestle  on  the  brink  of  a  precipice. 
Let  armed  international  strife  be  viewed  as  it  really  is 

—  senseless  as  the  now  dying  duello.  Let  the  navy  that 
represents  the  wealth,  the  best  engineering,  the  highest 
courage  and  skill,  of  our  age,  be  powerless  at  the  attack  of 
a  swarm  of  trifling  gnats  like  Gulliver  bound  by  Lilliputians 

-  what  happens  then?  It  is  a  reductio  ad  absurdum. 
Destructive  war  becomes  so  superlatively  destructive  as  to 
destroy  itself. 

There  is  only  one  other  way.  Let  the  two  rival 
Powers  on  whom  the  peace  of  the  world  depends  set- 
tle their  difficulties  —  surely  the  earth  must  be  big 
enough  for  both !  —  and  then  as  one  would  gently  but 
firmly  take  away  from  a  small  boy  his  too  destructive 
toy  rifle,  spike  the  guns  and  scuttle  the  ships,  their  own 
and  all  the  rest,  leaving  to  some  unambitious  and  neutral 
power  the  prosaic  task  of  policing  the  world.  Here  is  a 
work  for  red  blood  and  national  self-consciousness.  If 
war  were  ever  needed  for  man's  best  development,  other 
things  will  answer  now.  The  torn  bodies  and  desolated 
homes  of  millions  of  men  have  paid  the  price  demanded. 
No  imaged  hell  can  surpass  the  unnamed  horrors  that 
our  fathers  braved. 

" Enforced  disarmament!"  Why  not?  Force  (and  pub- 
lic opinion)  have  abolished  private  duels.  Why  not  na- 
tional duels  as  well?  Civilization's  control  of  savagery 


2O4  Flying  Machines  Today 

always  begins  with  compulsion.  For  a  generation,  no 
first-class  power  has  had  home  experience  in  a  serious 
armed  conflict.  We  should  not  willingly  contemplate 
such  experience  now.  We  have  too  much  to  do  in  the  world 

to  fight. 

***** 

The  writer  has  felt  some  hesitancy  in  letting  these  words 
stand  as  the  conclusion  of  a  book  on  flying  machines:  but 
as  with  the  old  Roman  who  terminated  every  oration  with 
a  defiance  of  Carthage,  the  conviction  prevails  that  no 
other  question  of  the  day  is  of  comparable  importance; 
and  on  a  matter  of  overwhelming  consequence  like  this  no 
word  can  ever  be  out  of  place.  The  five  chief  powers  spent 
for  war  purposes  (officially,  as  Professor  Johnson  puts  it, 
for  the  " preservation  of  peace")  about  $1,000,000,000  in  the 
year  1908.  In  the  worst  period  of  the  Napoleonic  opera- 
tions the  French  military  and  naval  budget  was  less  than 
$100,000,000  annually.  Great  Britain,  on  the  present  peace 
footing,  is  spending  for  armament  more  rapidly  than  from 
1793  to  1815.  The  gigantic  "War  of  the  Spanish  Succes- 
sion" (which  changed  the  map  of  Europe)  cost  England  less 
than  a  present  year's  military  expenditure.  Since  the 
types  for  these  pages  have  been  set,  the  promise  of  interna- 
tional peace  has  been  distinctly  strengthened.  President 
Taft  has  suggested  that  as,  first,  questions  of  individual 
privilege,  and,  finally,  even  those  of  individual  honor,  have 
been  by  common  consent  submitted  to  adjudication,  so 
also  may  those  so-called  "issues  involving  national  honor'* 


Aerial  Warfare  205 

be  disposed  of  without  dishonor  by  international  arbitration. 
Sir  Edward  Grey,  who  does  not  hesitate  to  say  that  increase 
of  armaments  may  end  in  the  destruction  of  civilization 
unless  stopped  by  revolt  of  the  masses  against  the  increas- 
ing burdens  of  taxation,  has  electrified  Europe  by  his  recep- 
tion of  the  Taft  pronouncement.  England  and  the  United 
States  rule  one-third  the  inhabitants  of  the  earth.  It  is 
true  that  a  defensive  alliance  might  be  more  advantageous 
to  the  former  and  disagreeably  entangling  to  the  latter; 
but  a  binding  treaty  of  arbitration  between  these  powers 
would  nevertheless  be  a  worthy  climax  to  our  present  era. 
And  if  it  led  to  alliance  against  a  third  nation  which  had 
refused  to  arbitrate  (led  —  as  Sir  Edward  Grey  suggests 
-  by  the  logic  of  events  and  not  by  subterranean  device) 
would  not  such  be  the  fitting  and  conclusive  outcome? 

The  Taft- Grey  program  —  one  would  wish  to  call  it 
that  —  has  had  all  reputable  endorsement;  in  England, 
no  factional  opposition  may  be  expected.  Our  own  jingoes 
are  strangely  silent.  Mr.  Dillon's  fear  that  compulsory 
disarmament  would  militate  against  the  weaker  nations  is 
offset  by  the  hearty  adherence  of  Denmark.  A  resolution 
in  favor  of  the  establishment  of  an  international  police  force 
has  passed  the  House  of  Commons  by  a  heavy  majority. 
It  looks  now  as  if  we  might  hope  before  long  to  re-date  our 
centuries.  We  have  had  Olympiads  and  Years  of  Rome, 
B.C.  and  A.D.  Perhaps  next  the  dream  of  thoughtful 
men  may  find  its  realization  in  the  new  (and,  we  may 
hope,  English)  prefix,  Y.P. —  Year  of  Peace. 


Books   on   Aeronautics 


FLYING  MACHINES  TO-DAY.    By  WILLIAM  D.  ENNIS,  M.  E.,  Professor 
of  Mechanical  Engineering,  Polytechnic  Institute,  Brooklyn. 

Umo.,  cloth,  218  pp.,  123  illustrations $1.50  net 

CONTENTS  :  THE  DELIGHTS  AND  DANGERS  OF  FLYING— Dangers  of  Aviation— What 
it  is  Like  to  Fly.  SOARING  FLIGHT  BY  MAN— What  Holds  it  Up.  Lifting  Power.  Why 
eo  Many  Sails.  Steering.  TURNING  CORNERS— What  Happens  When  Making  a  Turn. 
Lateral  Stability.  Wing  Warping.  Automatic  Control.  The  Gyroscope.  Wind  Gusts. 
AIR  AND  THE  WIND — Sailing  Balloons.  Field  and  Speed.  GAS  AND  BALLAST — 
Buoyancy  in  Air.  Ascending  and  Descending.  The  Ballonet.  The  Equilibrator. 
DIRIGIBLE  BALLOONS  AND  OTHER  KINDS — Shapes.  Dimensions.  Fabrics.  Framing. 
Keeping  the  Keel  Horizontal.  Stability.  Rudders  and  Planes.  Arrangement  and 
Accessories.  Amateur  Dirigibles.  Fort  Omaha  Plant.  Balloon  Progress.  QUESTION 
OP  POWER— Resistance  of  Aeroplanes.  Resistance  of  Dirigibles.  Independent  Speed 
and  Time-table.  Cost  of  Speed.  Propellor.  GETTING  UP  AND  DOWN  ;  MODELS  AND 
GLIDERS;  AEROPLANE  DETAILS  — Launching.  Descending.  Gliders.  Models. 
Balancing.  Weights.  Miscellaneous.  Things  to  Look  After.  SOME  AEROPLANES- 
SOME  ACCOMPLISHMENTS.  THE  POSSIBILITIES  IN  AVIATION— Case  of  the  Dirigible.  The 
Orthopter.  The  Helicopter.  Composite  Types.  What  is  Promised.  AERIAL  WARFARE. 

AERIAL  FLIGHT.    Vol.  I.   Aerodynamics.    By  F.  W.  LANCHESTER. 
8vo.,  cloth,  438  pp.,  162  illustrations $6.00  net 

CONTENTS:  Fluid  Resistance  and  Its  Associated  Phenomena.  Viscosity  and  Skin 
Friction.  The  Hydrodynamics  of  Analytical  Theory.  Wing  Form  and  Motion  in  the 
Peritery.  The  Aeroplane.  The  Normal  Plane.  The  Inclined  Aeroplane.  The 
Economics  of  Flight.  The  Aerofoil.  On  Propulsion,  the  Screw  Propeller,  and  the 
Power  Expended  in  Flight.  Experimental  Aerodynamics.  Glossary.  Appendices. 

Vol.  II.   Aerodonetics.                                       By  F.  W.  LANCHESTER. 
8vo.,  cloth,  433  pp.,  208  illustrations $6.00  net 

CONTENTS:  Free  Flight.  General  Principles  and  Phenomena.  The  Phugoid 
Theory— The  Equations  of  the  Flight  Path.  The  Phugoid  1852-1872.  Dirigible 
Balloons  from  1883-1897;  1898-1906.  Flying  Machine  Theory— The  Flight  Path 
Plotted.  Elementary  Deductions  from  the  Phugoid  Theory.  Stability  of  the  Flight 
Path  as  Affected  by  Resistance  and  Moment  of  Inertia.  Experimental  Evidence 
and  Verification  of  the  Phugoid  Theory.  Lateral  and  Directional  Stability.  Review  of 
Chapters  I  to  VII,  and  General  Conclusions.  Soaring.  Experimental.  Aerodonetics. 

AERIAL  NAVIGATION.    A  practical  handbook  on  the  construction 
of  dirigible  balloons,  aerostats,  aeroplanes  and  aeromotors,  by 

FREDERICK  WALKER.    12mo.,  cloth,  151  pp.,  100  illustrations.  .$3.00  net 

CONTENTS:  Laws  of  Flight.  Aerostatics.  Aerostats.  Aerodynamics.  Screw 
Propulsion.  Paddles  and  Aeroplanes.  Motive  Power.  Structure  of  Air-Ships  and 
Materials.  Air  Ships.  Appendix. 

AEROPLANE    PATENTS.     By  ROBERT  M.  NEILSON.    8vo.,  cloth,  101 
pp.,  77  illustrations $2.00  net 

CONTENTS:  Advice  to  Inventors.  Review  of  British  Patents.  British  Patents  and 
Applications  for  Patents  from  1860  to  1910,  Arranged  in  Order  of  Application.  British 
Patentees,  Arranged  Alphabetically.  United  States  Patents  from  1896  to  1909,  Arranged 
in  Order  of  Issue.  United  States  Patentees,  Arranged  Alphabetically. 

(OVER) 


THE  PRINCIPLES  OF  AEROPLANE  CONSTRUCTION.  By  RANKIN 
KENNEDY,  C  E.  8vo.,  cloth,  145  pp.,  51  diagrams $1.50  net 

CONTENTS:  Elementary  Mechanics  and  Physics.  Principles  of  Inclined  Planes. 
Air  and  Its  Properties.  Principles  of  the  Aeroplane.  The  Carves  of  the  Aeroplane. 
Centers  of  Gravity:  Balancing;  Steering.  The  Propeller.  The  Helicoptere.  The  Wing 
Propeller.  The  Engine.  The  Future  of  the  Aeroplane. 

HOW  TO  DESIGN  AN  AEROPLANE.  By  HERBERT  CHATLEY. 
16mo.,  boards,  109  pp.,  illustrated  (Van  Nostrand's  Science  Series).  .  .  .50  cents 
CONTENTS:  The  Aeroplane.  Air  Pressure.  Weight.  Propellers  and  Motors. 
Balancing.  Construction.  Difficulties.  Future  Developments.  Cost.  Other  Flying- 
Machines  (Gyroplane  and  Oriuthoptere). 

HOW  TO  BUILD  AN  AEROPLANE.  By  ROBERT  PETIT.  Translated 
from  the  French  by  T.  O'B.  Hubbard  and  J.  H.  Ledeboer.  8vo.,  cloth,  131  pp., 
93  illustrations $1 .50  net 

CONTENTS:  General  Principles  of  Aeroplane  Design.  Theory  and  Calculation. 
Resistance,  Lift,  Power,  Calculations  for  the  Design  of  an  Aeroplane,  Application  of 
Power,  Design  of  Propeller,  Arrangements  of  Surfaces,  Stability,  Center  of  Gravity,  etc. 
Materials.  Construction  of  Propellers.  Arrangements  for  Starting  and  Landing.  Controls. 
Placing  Motor.  The  Planes.  Curvatures.  Motors. 

AIRSHIPS,  PAST  AND  PRESENT.  Together  with  chapters  on  the 
use  of  balloons  in  connection  with  meteorology,  photography, 
and  the  carrier  pigeon.  By  A.  HILDEBRANDT,  Captain  and  Instructor 

in  the  Prussian  Balloon  Corps.  Translated  by  W.  H.  Story.  8vo.,  cloth,  361  pp., 
222  illustrations $3.50  net 

CONTENTS  :  Early  History  of  the  Art.  Invention  of  the  Air  Balloon.  Montgolfieres, 
Charlieres,  and  Rozieres.  Theory  of  the  Balloon.  Development  of  the  Dirigible  Bal- 
loon. History  of  the  Dirigible  Balloon,  1852-1872.  Dirigible  Balloons  from  1883-1897; 
1898-1906.  Flying  Machines.  Kites.  Parachutes.  Development  of  Military  Ballooning. 
Ballooning  in  Franco-Prussian  War.  Modern  Organization  of  Military  Ballooning  in 
France,  Germany,  England  and  Russia.  Military  Ballooning  in  Other  Countries.  Balloon 
Construction  and  the  Preparation  of  the  Gas.  Instruments.  Ballooning  as  a  Sport. 
Scientific  Ballooning.  Balloon  Photography.  Photographic  Outfit  for  Balloon  Work. 
Interpretation  of  Photographs.  Hectography  by  Means  of  Kites  and  Rockets.  Carrier 
Pigeons  for  Balloons.  Balloon  Law. 


D.  VAN  NOSTRAND  CO.,  Publishers 

23   MURRAY  and   27   WARREN  STREETS,  NEW  YORK 


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